The Cactus Page

Ariocarpus fissuratus  (Engelmann) K. K. Schumann 1894 (Living Rock Cactus)

 
Native to Northern Mexico and Texas.
Photo: Big Bend National Park, Texas.

Ariocarpus retusus  Scheidweiler 1838
Name: Latin retusus = blunt tip 
This somewhat variable plant is the type species for the genus. The rosette of spineless tubercles is supported by a subterranean tuberous body which requires excellent drainage.
 
Native to the high Chihuahuan desert in the Mexican states of Coahuila, Nuevo León, San Luis Potosi, Tamaulipas, and Zacatecas, growing on limestone and gypsum.

Ariocarpus scaphirostris  F. Boedeker 1930
Syn. Ariocarpus scapharostrus  Boedecker 1930
Name: Latin scaphe = peak + rostrum = face 
The tubercles of the mature plant are spineless, but seedlings have spines.
 
Native to the Mexican state of state of Nuevo León.

Arrojadoa bahiensis  (P.J. Braun & Esteves ) N.P. Taylor & Eggli 1994
Named for: the Bahia state of Brazil 
This species has the thickest body in the genus and grows up to 3ft tall. The spherical to cylindrical stems have 9 - 14 ribs. The areoles, closely spaced along the apex of the ribs, produce cream-coloured wool and long brownish needle-shaped spines. Pink tubular flowers with white inner petals are produced near to the growing point followed by pink berries.
 
Native to central Bahia, Brazil where it is considered endangered.

Astrophytum myriostigma  Lemaire 1839 (Turk's Head Cactus)
Name: Greek myrios = innumerable + stigma = stain (many-dotted) 
The three to seven, usually five-ribbed solitary plant body is covered with thousands of tiny dots of white trichomes to a variable extent. There are no spines. Yellowish, sweetly-scented flowers with many petals are produced at the apex of the plant and are followed by a large (1 inch) red fruit.
 
Native to the Mexican states of Coahuila, Durango, Nuevo León, San Luis Potosí and Tamaulipas. The plant should be watered from below to preserve the white flocking. Some all-green horticultural selections have no trichomes.
Photo: Benno Stander 2014, of a cultivated plant in South Africa.

Astrophytum myriostigma quadricostatum  M. Mittler 1841
A nursery-selected form with four ribs instead of the more usual five ribs. Such plants also occur in the wild population. Flowers are pale yellow. Further selections have led to all-green plants without white trichomes and several named cultivars with distinctive patterns of white trichomes.

Astrophytum ornatum  (De Candolle) Weber ex Britton & Rose 1922 (Bishop's Cap)
Name: Latin ornatus = decorated, referring to the woolly flakes on the body 
This is the largest species of Astrophytum. The five to ten, usually eight-ribbed solitary plant body has bands of white flocking, to a very variable extent, in some variants becoming near confluent. Yellowish flowers with many petals are produced at the apex of the plant.
 
Native to canyons and limestone cliffs in the Mexican states of Hidalgo, Queretaro and Guanajuato.

Blossfeldia liliputana  Werdermann 1937
Named for: fictional country of Lilliput inhabited by a race of tiny people (Gulliver's Travels, 1726, Jonathan Swift) 
The tiny plant body less than half an inch in diameter has no rib, tubercles or spines but is dotted with areoles bearing white hairs. Unlike most other cacti, Blossfeldia liliputana has no thickened outer cuticle but instead appears to be poikilohydric (can withstand dessication). The small flowers are white or pale yellow with bright yellow stamens.
 
Native to a range from Southern Bolivia to North-Western Argentina, growing in rock crevices on cliffs. Grafting accelerates growth but produces unnatural bloated golf ball sized plants.

Calymmanthium substerile  F. Ritter 1962
Syn. Calymmanthium fertile F. Ritter 1966 (designat. typi omissa.)
Name: substerile because the original discovery was of a non-flowering clone. 
This cactus grows as a large shrubby tree, 25ft or more tall, with multiple stems from the base. The stem is segmented according to periods of growth, with three or four notched wing-like ribs furnished with areoles bearing long white to buff spines. This is a night flowering cactus. The large white to pink flowers are produced at the end of a stem-like segment which acts as a floral tube and within which they remain partly sheathed.
 
Native to mountains of Peru. Not commonly in cultivation in greenhouses because of its size, but can be seen in some tropical and sub-tropical botanic gardens.

By US Route 60 Phoenix-Wickenburg, Az.	By US Route 86, South of Why, Az.
Desert Botanic Garden Phoenix, Az.	By US Route 86, South of Why, Az.

Carnegiea gigantea  (Engelmann) Britton & Rose 1908 (Saguaro)
Syn. Cereus giganteus  Engelmann 1848,  Pilocereus giganteus  (Engelmann) Rümpler 1885
Name: Saguaro is Mexican-Spanish from a native name. 
The Saguaro cactus has a tall, ribbed columnar stem up to 30ft tall, often branching with age. A Saguaro may live for more than 200 years, growing very slowly at first in the shelter of a 'nurse bush' and then a little faster once it has reached several feet in height. The branches tend to curve upwards unless affected by cold in which case they develop a permanent droop. The trunk is covered by a waxy skin, becoming corky low down and there are 2 inch spines along the ribs. The ribbed trunk allows the stem to expand and contract without splitting, depending on the availability of water. There is a short tap root but most of the roots form a shallow network to a radial distance similar to the height of the cactus, providing a large area from which to scavenge moisture. In the Spring, white trumpet-shaped flowers with yellow stamens are produced around the apex of the stem, followed by juicy red fruit. The Saguaro is the state flower of Arizona.
 
Native to the Sonoran deserts of Arizona, Eastern California and the Mexican state of Sonora. The Tohono O'odham Indians valued Saguaro fruit which can be used to make preserves or fermented into wine. The internal wooden ribs of the cactus were used for construction and the spines as sewing needles. The Saguaro cactus is a common emblem on artistic and advertising material to imply a connection with the South-West USA. Several Western films feature Saguaros well outside their natural range.
 
Saguaros seem a little more prone to abnormal growths than other cacti. Plants with a cristate growing point are not uncommon, although a tiny proportion of all Saguaros. The cause is unknown but may reflect damage by frost or other agents.

Cereus hankeanus F.A.C. Weber 1897
Syn. Cereus forbesii spiralis  Otto (Spiraled Cereus)
This shrubby cactus produces a candelabra of ascending glaucous-green 4 - 8 angled stems up to 5 in diameter and 15ft tall. Stems may grow with stright ribs or adopt a spiral mode of growth in either direction. The margins of each rib bears well-spaced clusters of 2 - 5 radial light-brown spines with 1 - 3 stouter central spines. White flowers are followed by large purple fruits.
 
Cereus hankeanus is native to Argentina, Bolivia, and Paraguay. The spiraled arm form is seen in Brazil.

Cereus stenogonus   K.Schumann 1899
This tree-like cactus has branching stems that eventually form a huge candelabra up to 30ft tall. Flowers are greenish-white on the end of a long flower tube.
 
Native to low elevations in Argentina, Paraguay and Uruguay

Cleistocactus candelilla  Cárdenas 1952
Name: Spanish candelilla = small candle  
Tubular pink-red flowers form mostly on the sunny side of the stem and are followed by pink fruits.
 
Native to the Bolivian regions of Cochabamba, Potosí and Santa Cruz and especially Amboró National Park.

Cleistocactus hyalacanthus  (K.M. Schumann) Roland-Gosselin 1904

 
Native to Argentina and Bolivia.

Cleistocactus semaipatanus  (Cárdenas) D.R. Hunt 1987
Syn. Bolivicereus samaipatanus Cárdenas 1951
Syn. Borzicactus samaipatanus (Cárdenas) Kimnach 1960
Name: grows near Samaipata in Bolivia 
The long green stems with 14 - 17 ribs can grow upright as a shrubby plant for a while but tend to become prostrate, forming a tangled mat. The closely-spaced areoles produce 13 - 40 golden spines. Attractive tubular pink to red flowers with purple stamens are produced in early Summer. These flowers open wide which is why this cactus was originally classified as a Borzicactus. The small fruits are red with white or brown wool.
 
Native to the Andean Valleys in the Department of Santa Cruz, Bolivia but common worldwide as it is used for dry landscaping in warm climates. Needs a cool Winter to flower freely.

Cleistocactus sepium (Kunth) A.Weber 1904
See: Matucana weberbaueri

Cleistocactus smaragdiflorus  (F.A.C.Weber) Britton & Rose 1920 (Emerald Flowering Cleistocactus)
Name: Latin smaragdinus = emerald green + florus = flower 
Syn. Cleistocactus rojoi Cárdenas 1956
Named for : Leandro Rojo one of Cárdenas' field trip companions. 
The tubular red flowers with a greenish tip open minimally but the style is exserted. The green colour seems to fade as the flower opens.
 
Native to Bolivia, Paraguay and Argentina.

Cleistocactus strausii  (Heese) Backeberg 1934 (Silver Torch Cactus)
Syn. Pilocereus straussii  
Named for: L. Straus (1862 - 1934) German merchant & cactus lover from Bruchsal, co-founder Deutsche Kakteen-Gesellschaft DKG 
Native to high mountain ranges of Southern Bolivia and Northern Argentina, growing above 9800 ft.

Cleistocactus tarijensis  Cárdenas 1956
Named for: Bolivian Department of Tarija 
The tubular red flowers open at their tip with the many petals producing a frilly appearance.
 
Native to Bolivia.

Cleistocactus winteri  D.R. Hunt 1988 (Golden Rat Tail)
Syn. Borzicactus aureispinus  (F.Ritter) G.D.Rowley 1962
Syn. Hildewintera aureispina  (F.Ritter) F.Ritter 1966
Named for: Hildegarda Winter (1893-1975), sister of cactus expert Friedrich Ritter. 
This succulent plant forms mounds of tangled recumbent stems whose surface is covered with many short golden spines. The small pink flowers open more fully than those of many other Cleistocactus.
 
Native to Argentina and Uruguay. Good subject for a hanging basket. Has been hybridised with other cacti.

Cleistocactus x  
A columnar hybrid with large pink tubular flowers opening fully at their tip.
 

Copiapoa barquitensis  F. Ritter (1960) (nom. inval.)
Named for: Barquito = coastal town and port in Chile 
Copiapoa hypogaea  F. Ritter 1960, Copiapoa hypogaea var. barquitensis  F. Ritter 1980
Name: Greek hypogaea = underground, referring to the sunken nature of the plant body. 
This cactus forms clumps of brown to gray-green, tuberculate bodies with wooly tubercles bearing one or more short spines, often absent on older parts of the plant.
 
Native to the Atacama desert of Chile.
Photo: Holly Gate Cactus Nursery reference collection

Copiapoa humilis  (Philippi) P.C. Hutchison 1953
Name: Latin humilis = low, small 
This small cactus forms clumps of brown to gray-green, tuberculate bodies with wooly tubercles bearing 7 - 13 short radial spines and 1 - 4 central spines. There is a large tap root below the body. The pale yellow flowers are scented.
 
Native to a wide range of the Atacama desert and mountain base, North and South of the type locality, Paposo, Antofagasta, Chile.

Coryphantha calipensis  H. Bravo Hollis 1992
Name: refers to the small town of Calipan in the Mexican State of Puebla 
Flowers are yellow.
 
Photographed at RBG Kew.

Coryphantha echinus  (Engelmann) Britton & Rose 1923 (Texas Pincushion)
Syn. Mammillaria echinus  Engelmann 1856
Name: Greek ekhinos = hedgehog, sea urchin 
The solitary globular plant body has areoles with 16 - 30 thin radial spines and 0 - 4 stout central spines. In young plants the central spines are absent, only developing with age. The large flowers are bright yellow with golden stamens and are folllowed by green ovoid fruit.
 
Native to West Texas and the Mexican states of Coahuila, Chihuahua, growing on limestone soils.
Photo: Los Caballos, Brewster County, Texas.

Dendrocereus nudiflorus  Britton & Rose 1920 (Goblet Flower, Flor De Copa, Cimarron)
Syn. Cereus nudiflorus  Engelmann ex Sauvalle 1869
Name: Latin nudus = naked + florus = flower 
This large tree-like cactus has a corky brown branching trunk crowned with a mass of thick, light green, three to five-angled upright or pendulous succulent stems. Stem margins are undulate with areoles set in notches. Areoles produce up to fifteen short, grey spines which are more pronounced on immature stems and may be absent on mature growth. The fragrant nocturnal funnel-shaped flowers have smooth green floral tubes and white to pale pink petals. Flowers are followed by spineless, rounded green fruits full of small flat seeds.
 
This cactus is endemic to dry, coastal cactus scrub of Cuba where the species is threatened by habitat destruction and agriculture. Rare in cultivation because of its size, although the fruit is edible. These cacti are said to grow for hundreds of years. The oldest specimen (left) is known as 'El Patriarca' and thought to be at least 500 years old.

Echinocactus grusonii  H. Hildmann 1886 (Mother in Law's Cushion, Golden Barrel Cactus)
Named for: Hermann August Jacques Gruson (1821 - 1895) German engineer & cactus collector 
The spherical green plant body of a mature plant has up to 35 prominent ribs edged with golden-yellow spines. Young plants have somewhat tuberculate ribs. With age, the body may become 4 ft in height and more cylindrical. Mature plants can offset to form a small clump. As with other barrel cacti, the body tends to lean to the south or southwest so that the spines can better filter the fierce sunlight. Selected cultivars are known with white spines or without spines. Yellowish hairs produced from the areoles form a wooly mat around the top of a mature plant.
 
A ring of small (for the size of the plant) yellow flowers are produced around the wooly crown in late Spring or early Summer and are followed by small yellowish fruits terminated by the dried flowers. Fruits are full of small brown seeds from which it is easy to grown new plants. Seedlings are initially bi-lobed.
 
Echinocactus grusonii is native to the Mexican states of Querétaro and Zacatecas. Much of the population was lost when the Zimapán Dam and reservoir was built in Hidalgo although conservationists rescued many of the plants. Echinocactus grusonii is a popular feature plant for dry landscaping in warm climates.

Echinocactus horizonthalonius  Lemaire 1839 (Eagle's Claw, Devil's Head)
Name: Latin horizonthal = horizontal + halos = flat 
The blue-green flattened-globose to cylindrical body is always solitary with typically 8 ribs. The areoles have 5 - 7 radial spines recurved against the body and 3 - 5 erect radial spines. The spiny cage surrounding the plant body often persists after death of the plant and can sometimes be found rolling around in the wind. Flowers are pale pink to magenta with a wooly floral tube, produced in late Spring to early Summer followed by fruits covered in wool.

Native to the Chihuahuan Desert from Arizona, New Mexico, Texas and into North-Eastern Mexico and quite common in places. Delightful plants in their habitat but very difficult and slow-growing in cultivation.
 
Left: This specimen of Echinocactus horizonthalonius had rather short stubby spines compared to the rest of the population in the same area. Maverick Mountain, Texas.

Echinocactus platyacanthus  Link & Otto 1827
Syn. Echinocactus ingens  Zuccarini ex Pfeiffer 1837
Name: Greek platyacanthus = with wide thorns 
This barrel cactus eventually grows larger than any other, up to 8 ft tall and 5ft wide.
 
Widely-distributed across North-East and Central Mexico.

Echinocereus berlandieri  (Engelmann) J.N. Haage 1859
Named for: Jean Louis Berlandier (1805-1851) Belgian naturalist. 
The flabby dark green stems have 5 - 7 ribs. The areoles have 1 - 3 brown central spines up to 2cm long and 6 - 9 shorter whiteish radial spines.
 
Native to the Mexican states of Nuevo León and Tamaulipas and Texas in the USA. Photo: Holly Gate Cactus Nursery reference collection

Echinocereus brandegeei  (J.M. Coulter) K. Schumann 1898
Named for: Townshend Stith Brandegee (1843 - 1925) US botanist and plant collector. 
The stems offset freely at their base to form large spiny clumps. Fuchsia-pink flowers with darker centres and yellow stigmas are produced in late Summer.
 
Native to Baja California including the islands in the Gulf of California.

Echinocereus chisoensis  W.T. Marshall 1940 (Chisos Hedgehog Cactus)
Syn. Echinocereus fobeanus, Echinocereus metornii Name: From the Chisos Mountains of Texas. 
The solitary cylindrical stem has 10 - 16 strong ribs. The areoles have 1 - 6 central spines and 11 - 17 fine radials. The funnel-shaped flower has a woolly floral tube with clusters of spines and is bright pink with a lighter or darker centre, yellow stamens and green stigma.
 
A rare plant native to the Chihuahuan desert of the Big Bend country of Texas and Northern Mexico.
Photo: Big Bend National Park, Texas, in the presence of Club Chollas.

Echinocereus chloranthus  (Engelmann) J.N.Haage 1859 (Green Flowered Torch Cactus)
Syn. Echinocereus viridiflorus subsp. chloranthus  (Engelmann) N.P.Taylor 1997
Name: Greek chlor = green + anthus = flower 
This variable cactus has flowers ranging from green, brown or wine-coloured and dense spination ranging from white to reddish brown. Native to Western Texas, South-Eastern New Mexico, and Northern Mexico, growing on igneous soils.
Photo: Los Caballos, Brewster County, Texas.

Echinocereus coccineus  Engelmann 1848 (Strawberry Hedgehog)

 
Native to South-Western USA, Arizona, California, Colorado, New Mexico, Nevada, Utah, Texas and the Mexican states of Coahuila, Chihuahua and Sonora.

Echinocereus dasyacanthus  Engelmann 1848 (Texas Rainbow)
Syn. Echinocereus pectinatus var. dasyacanthus  (Engelmann) W. Earle ex N. P. Taylor 1984
Name: Greek dasys = thick + akanthos = thorn 
This cactus forms short columns, occasionally offsetting at the base of higher up. The stem has 15 - 20 ribs but these are largely obscured by the dense bristly spines. Areoles produce 16 - 24 radial and 3 - 10 short central spines which vary in colour from white, pale yellow to browns and purple, depending on the growing conditions. Annual growth rings are often marked by spines of different colours. The large yellow flowers with a greenish throat and green stigma make this an exceptionally attractive species. The outer petals may have a darker mid-stripe.
 
Native to the Chihuahuan desert, Texas, Oklahoma, Southern New Mexico and Northern Mexico, usually on limestone soils. Photo: Limestone cliffs near Terlingua.

Echinocereus davisii Houghton 1931
Syn. Echinocereus viridiflorus subs. davisii (Houghton) N.P.Taylor 1997
Named for: Alva Raymond Davis, Prof. Plant Physiology (1887-1965), discovered this species. 
This dwarf cactus has a tuberous root supporting a usually solitary dark green stem up to a 1.5 in tall with 6 - 10 ribs and pale yellow-green lemon-scented flowers in early Spring. Areoles have 8 - 14 radial spines, an occasional single central spine and little wool. The small size and sparse wool on areoles distinguihes this species from Echinocereus viridiflorus.
 
Native to Brewster County in Trans-Pecos West Texas near Marathon where a small population grows on quartz sandy soil on low, rocky hills. In cultivation, stems grow a little larger up to 3 in with time and may offset, flowering freely at a small size.

Echinocereus engelmannii  (Parry ex Engelmann) Lemaire 1868

 
Photo: Holly Gate Cactus Nursery reference collection

Echinocereus enneacanthus  Engelmann 1848
The soft, green stems initially grow upright, becoming recumbent as they lengthen and offsetting from their base to produce a sprawling clump with a flabby appearance. Stems have 7 - 12 ribs with well-spaced areoles bearing 5 - 9 curved radial spines and 1 - 3 short central spines. In the Spring bright-pink to reddish diurnal flowers are produced. The edible fruits are yellowish-green to reddish and furnished with glochids.
 
Native to Chihuahuan deserts of New Mexico, Texas and the Northeastern Mexican states of Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí and Sonora.
Photo: Big Bend National Park

Echinocereus lauii  G. Frank 1978
Named for: Dr. Alfred Bernhard Lau (1928 - 2007) German missionary and cactus enthusiast. 
This small cactus clumps up by offsetting from its base. The green ribbed stems are mostly obscured by the 20 radial spines and white hairs from each areole. Areoles also produce four central spines. Pink funnel-shaped flowers are followed by spherical greenish spiny fruits.
 
Native to the Mexican state of Sonora.

Echinocereus nicholii  (L.D.Benson) B.D. Parfitt 1987 (Golden Hedgehog, Nichol's Hedgehog)
Syn. Echinocereus engelmannii var. nicholii L.D.Benson 1944
Named for: Andrew Alexander Nichol (1895-1961) American biologist 
This rare cactus forms large clumps of stems up to 2 ft tall, with a dense golden spination which marks it out in the field as something different. Areoles are well-spaced and produce 4 - 8 long yellow central spines up to 3 in long and 8 - 12 radial spines. The small flowers are pink and followed by greenish-brown fruit.
 
Native to Sonoran desert of central Arizona and Northern Mexico.
Photo: 20 miles North of Las Vegas, must be the extreme Northern end of its range.

Echinocereus pectinatus  (Scheidweiler) Engelmann 1848 (Texas Rainbow)
Name: Latin pectinatus = comb-like referring to the spines 
The short columnar green body is usually solitary but old plants may branch. There are up to 30 white to pink radial spines but the central spines are absent or a few very short ones. The funnel-shaped flower is bright pink and followed by a purple-green fruit with dehiscent spines.
 
Native to South-Western USA, Texas, New Mexico.
Echinocereus pectinatus var. dasyacanthus (Engelmann) W. Earle ex N. P. Taylor 1984
is a taller columnar plant with a large yellow flower.

Echinocereus pensilis  (Brandegee) J.A. Purpus 1908
Syn. Morangaya pensilis  (K. Brandegee) G.D. Rowley 1974
 
Photographed at Holly Gate Cactus Nursery reference collection

Echinocereus polyacanthus  Engelmann 1848 (Giant Claret Cup)
Syn. Echinocereus triglochidiatus var. polyacanthus (Engelmann) Benson 1944
Name: Latin polyacanthus = many spined 
This variable species forms large clumps of dozens of stems, producing bright red blooms with whiteish throats and rounded petals in Spring to early Summer.
 
Native to South-Eastern Arizona, Western New Mexico, North-Western Mexico including Baja California.

Echinocereus polyacanthus subs. mombergerianus  (G. Frank) Breckwoldt 1996
Syn. Echinocereus mombergerianus G. Frank 1990, Echinocereus polyacanthus var. pacificus (Engelmann) N.P.Taylor 1984
Named for: Peter Momberger who dicovered this species 
The densely-spined stems clump up to form cushions 2 - 3ft in diameter with over a hundred stems. The red to orange flowers with paler throats and green stigmas are particularly showy.
 
Native to the Sierra San Pedro Martir of Baja California.

Echinocereus roetteri var. lloydii  (Britton & Rose) Backeberg 1960
Syn. Echinocereus x lloydii  Britton & Rose 1922,  Echinocereus x roetteri  (Engelmann) Rümpler 1866
 
This rare plant is probably a natural hybrid Echinocereus pectinatus var. dasyacanthus x Echinocereus coccineus. As such, individual plants may present a variable appearance.
 
Photographed: N. of Marathon, Texas - April 1990.

Echinocereus stramineus  (Engelmann) F. Seitz 1870 (Strawberry cactus)
Name: Latin stramineus = made of straw 
The many light-yellow spines make this clumping cactus look like a pile of old straw, distinguishing it from other Echinocereus, especially the otherwise similar E. enneacanthus. The light green stems have 11- 17 ribs with areoles bearing 7 - 10 radial and 2 - 4 central spines, largely obscuring the plant body. The bright pink flowers with yellow stamens and green stigma are produced in the Spring and are followed by juicy red fruit. Occasional white flowered plants have been reported in the Big Bend National Park.
 
Native to Trans-Pecos Texas and the Big Bend Country, New Mexico and the Mexican states of Coahuila, Chihuahua, and Nuevo León. The edible fruit are picked and sold in Mexican markets.

Echinocereus triglochidiatus  Engelmann 1848 (Claret Cup)
Name: Latin tri = three + glochidium = barbed hair or spine 
The green body has prominently tuberculate ribs. Despite the name, areoles often have more than 3 straight to curved spines. The grey radial spines (1 - 10) and central spines (1 - 4) are hard to tell apart. This widespread clumping cactus has several named varieties. However, considerable variation may be seen between adjacent clumps. The dark red to orange funnel-shaped flowers, sometimes with a pale base, have pink to purple stamens and a green stigma. Flowers are followed by juicy, edible yellow-green to pink fruit.
 
Native to Arizona, Southern California, Colorado, New Mexico, Nevada, Utah, Texas, and Mexico, growing on the desert floor and at elevations of up to 11,000 ft above sea level on both igneous and limestone soils. Seen flowering on the top of Emory Peak in the Chisos Mountains.
Photos: Los Caballos, Brewster County, Texas. Note: ants feeding on nectar in the left-hand picture.

Echinomastus intertextus  (Engelmann) Britton & Rose 1922 (Chihuahua Pineapple Cactus)
Syn. Neolloydia intertexta  (Engelmann) L.D. Benson 1969
Syn. Sclerocactus intertextus (Engelmann) N.P. Taylor 1987
Name: Latin intertextus = interwoven, referring to the spines 
The solitary globular to ovoid plant body with 11 - 13 tuberculate ribs is largely hidden by the interwoven spines. Areoles produce 13 - 25 curved white radial spines and 4 pink to grey central spines. The funnel-shaped flowers are pink or white and followed by spherical green fruit.
 
Native to a range from South-Eastern Arizona to West Texas and the Mexican states of Chihuahua and Sonora.
 
Upper left: Granite soil in front of Chisos Mountains, Big Bend National Park, Texas.
Lower left: Limestone soil Dog Canyon area, Big Bend National Park, Tx.

Echinomastus johnsonii  E.M. Baxter 1935 (Johnson's Pineapple Cactus)
Syn. Neolloydia johnsonii  (Parry ex Engelmann) L.D. Benson 1969
Syn. Sclerocactus johnsonii (Parry ex Engelmann) N.P. Taylor 1987
Named for: Joseph (Elias) Ellis Johnson (1817-1882) Mormon settler in Utah, amateur botanist, horticulturist & herbalist. 
This small barrel cactus has a green body with 18 - 21 ribs, mostly obscured by interlocking reddish-brown spines. Areoles have 4 - 9 central spines and 9 - 16 radial spines. The funnel-shaped flowers are magenta or yellow, followed by greenish fruits.
 
Native to arid limestone soils of the Mojave deserts of Arizona, California (Death Valley area), Nevada, Southern Utah. Very difficult in cultivation and often grown grafted.

Echinopsis backebergii  Werdermann 1931
Syn. Lobivia wrightiana  Backeberg 1937,  Lobivia backebergii  (Werdermann) Backeberg 1935 subsp. wrightiana (Backeberg) G.D. Rowley 1982
Named for: Curt Backeberg (1894 - 1966) German collector and classifier of cacti. 
Two subspecies are recognised: Echinopsis backebergii backebergii and Echinopsis backebergii wrightiana which some consider to be separate species. This solitary or clumping cactus has a globular green body with 15 ribs, becoming cylindrial with age. The areoles have 1 - 11 brown spines. The funnel-shaped flowers are pink to red with a white throat.
 
Native to the Andes mountains of Eastern Bolivia and Southern Peru, growing at up to 9800 ft above sea level.
 
 
Left: Echinopsis backebergii subsp. wrightiana  (Backeberg) M. Lowry 2005
Syn. Lobivia wrightiana  Backeberg 1937
has very long thin spines and pale lilac flowers with a paler throat.
Native to Huancavelica, Central Peru.

Echinopsis chamaecereus  H. Friedrich & Glaetzle 1983 (Peanut Cactus)
Syn. Chamaecereus silvestrii  (Spegazzini) Britton & Rose 1922
Named for: Filippo Silvestri (1873-1949) Italian entomologist & botanist. 
This mat-forming cactus has many long thin stems, initially erect but later decimbent, with 8 - 10 ribs profusely furnished with clusters of 10 - 15 small, bristly, radial spines. Peanut-sized offsets are produced along the main stems, detaching rather easily to start new plants. Funnel-shaped orange flowers are produced freely in late Spring and sporadically later on.
 
Native to the Andean mountains of Argentina and moderately frost-hardy when dry. Features in many colourful hybrids with other Echinopsis, especially Lobivia species with the hybrids known as Chamaelobivia. Echinopsis chamaecereus f. aureus is a yellowish chlorophyll-deficient mutant commonly seen grafted.

Echinopsis comarapana  Cárdenas 1957
Name: from Comarapa in the Bolivian province of Vallegrande. 
This cactus has short cylindrical gray-green stems with ten - twelve ribs bearing grayish areoles with one central spine and 9 - 11 thin radial spines. By offsetting, this cactus clumps up to form large cushions. The relatively-large flowers are white and funnel shaped.
 
Native to the Bolivian department of Santa-Cruz.

Echinopsis formosa  (Pfeiffer) Jacobi ex Salm-Dyck 1850
Name: Latin formosa = well formed, handsome 
A commonly solitary cactus, offsetting from the base with maturity. The light-green body has 27 - 50 ribs with areoles producing 9- 15 slightly curved radial spines and 2 - 9 brown central spines. The funnel-shaped flowers are bright yellow, orange to red.
 
Native to Argentina and Chile.

Echinopsis huascha  (Weber) Friedrich & G.D.Rowley 1974 (Red Torch Cactus, Argentine Hedgehog)
Named for: location in North-Western Argentina. 
This cactus grows upright at first, then becomes decumbent as the spiny, ribbed stem elongates. Stems typically have 14 - 17 ribs and areoles with 9 - 11 radial spines and 1 - 3 needle-like brown central spines. Basal offsetting produces a mat of sprawling stems. Flower colours range from golden-yellow to orange and red. Flower tubes are scaly with long brown hairs.
 
Native to Argentina and Bolivia.

Echinopsis pygmaea  R.E. Fries 1905
Syn. Lobivia pygmaea  (R. E. Fries) Backeberg 1935,  Mediolobivia eos var. roseiflora  Rausch 1972,  Rebutia pygmaea  (R. E. Fries) Britton & Rose 1922

 
This variable species has many (>60) synonyms. Current fashion favours Echinopsis.
Native to Bolivia and Argentina.

Echinopsis schieliana  (Backeberg) D. R. Hunt 1987
Syn. Lobivia schieliana Backeberg 1957
Named for: German cactophile Wolfgang Schiel (1904-1978) 
This small cactus forms clumps of dark reddish-green globose to cylindrical bodies, spidery golden spines and light red or dark gold flowers.
 
Native to a small area of North-West Bolivia (La Paz) and Peru, at altitudes arouind 10,000 ft above sea level.

Echinopsis spiniflora  (K. Schumann) A.Berger 1929
Syn. Acanthocalycium spiniflorum  (K. Schumann) Backeberg 1935
This cactus is usually solitary but may offset at its base. The dark green globular body has 9 - 15 ribs with areoles covered in brownish fluff and producing dark 5 - 10 brown to grey radial spines and 1 - 4 central spines. Flowers are white or shades of pink with yellow stamens. Flower buds and floral tubes are very hairy and scaly.
 
Native to Argentina.

Echinopsis aff. strigosa  (Salm-Dyck) Friedrich & G.D.Rowley 1974

 
Native to Argentina.

Echinopsis thelegona  (Weber) Friedrich & G.D. Rowley 1974
Syn. Trichocereus thelegonus  (Weber) Britton & Rose 1920
The spiny ribbed stems are about 3 inches in diameter and columnar, then decumbent as the stems elongate. Areoles have 6 - 7 radial spines and 1 central spine. The large fragrant flowers are white, opening at night and are followed by edible red fruit.
 
Native to low deserts of North-Western Argentina and Bolivia.

Epiphyllum hookeri  Haworth 1829 (Hooker's Orchid Cactus)
Named for: Sir William Hooker (1785 - 1865) Director of Royal Botanic Gardens, Kew. 
This species has wide flat stems with notched margins, a pronounced central mid-rib and occasional narrow triangular stem sections. The large white flower has many narrow petals with white stamens, and a yellow stigma with a purple tube. The fragrant blooms open at night.
 
Native to Central American and Caribbean rainforests including Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama. It is also naturalised in Florida USA.

Epiphyllum oxypetalum  (de Candolle) Haworth 1829 (Queen of the Night)
Named for: Sir William Hooker (1785 - 1865) Director of Royal Botanic Gardens, Kew. 
This Epiphyllum has a cylindrical stem branching at its end into wide flat pendulous stems with a midrib and notched margins. The large white flower has many narrow petals with white stamens, and a white stigma. The sweetly fragrant blooms open at night.
 
Native to tropical rain-forests of Central and South America including Mexico, Venezuela and Brazil and naturalised in other moist tropical climates. Typically grows hanging from trees and this lifestyle makes it suitable for hanging baskets.

Epi hybrid
This hybrid has a large white flower with brownish-yellow sepals that opens at night but usually lasts for two or three days. The flowers produce a very strong perfume of lilies in late evening into the night.
 
Of garden origin, but the parental species originate in the South American rainforests. Tolerates a cold dry Winter but no frost.

Epi hybrid cv. 'Reichskanzler Adolph Hitler'
A night-perfumed red flower with subtle hints of lilac inside that makes an interesting change from all-red flowers.
 
A variety raised by the German Epicacti hybridizer Curt Knebel in 1935. Renamed by the American Epiphyllum Society to 'Sherman E. Beahm' and known by some as 'Flying Fortress'. Original cutting obtained from the late Holly Gate Cactus Nursery.

Epithelantha micromeris  (Engelmann) Britton & Rose 1922 (Button cactus)
Name: Greek mikros = small + meros = parts, referring to the spines 
This tiny globose cactus occurs singly or in small groups, often in cracks in rocks and between gravel. The body is green with many very small tubercles but the high density of pectinate spines gives it a rough grey-white appearance. The stems often have a flat or concave centre. Tiny pink flowers are produced from near to the apex of tubercles at the top of the stem and are followed by eliptical or elongated shiny red fruits.
 
Widely spread across Arizona, New Mexico, Western Texas and the Mexican state of northern Chihuahua, often growing on limestone.

Escobaria albicolumnaria  Hester 1941 (Silver-Lace Cob Cactus)
A solitary cactus growing as a short column up to 10in tall. Plants occasionally branch and becomemulti-stemmed. Tubercles are grooved. Areoles produce 25 - 30 white radial spines and 11- 15 central spines. The small flowers are pink with a darker mid-stripe on the petals and are followed by yellowish-green fruits.
 
Native to limestone of Brewster County, Texas
Photo: On limy conglomerate above Boquillas Canyon, Big Bend National Park, Texas.

Escobaria hesteri  (Y. Wright) Buxbaum 1951

 
Photo: South of Marathon, Texas.

Escobaria sneedii  Britton & Rose 1923 (Sneed's pincushion cactus)
Named for: J.R. Sneed, plant collector. 
This small clumping cactus has prominent irregular white spines obscuring the green body. Flowers are bright to dull pink.
 
A rare plant thanks to over-collecting. Native to New Mexico, Texas, and the Mexican state of Chihuahua. Type locality is the Franklin Mountains of Texas.
Photo: Guadelupe Mountains National Park, Texas

Escobaria leeii ssp. leei (Rose ex Bödecker) D.R.Hunt 1997 (Lee's pincushion cactus)
Syn. Escobaria sneedii  Rose ex Bödecker 1933
Named for: Willis T. Lee, geologist who surveyed the park and collected this plant in 1925 
This cactus grows in large clumps of small stems with white spines obscuring the green body. Flowers are pale pink. It appears to be a juvenile (neotenic) form of E. sneedii.
 
Native to the Guadelupe Mountains of New Mexico, typically growing in cracks in limestone ridges and paving. It is rare through a very limited distribution within the Carlsbad Caverns National Park, but locally quite prolific.
Photos: Carlsbad Caverns National Park, Guadelupe Mountains, NM.

Escobaria missouriensis  (Sweet) D.R. Hunt 1978

 
Photograph: Robin Howard, Cheyenne Mountain State Park, Colorado. June 2008

Escobaria tuberculosa  (Engelmann) Britton & Rose 1923
This is the type species for the genus.
 
West of Terlingua, Texas.

Escobaria tuberculosa  (Engelmann) Britton & Rose 1923

 
Photo: Dog Canyon, Big Bend National Park, Texas.

Escobaria tuberculosa  (Engelmann) Britton & Rose 1923
 
Photos: cultivated plants.

Escobaria vivipara  (Nuttall) Buxbaum 1951 (Spinystar Cactus)

 
Native to a wide range of Northern America from Canada into Mexico.
Photo: Escobaria vivipara in fruit. Marathon, Texas.

Espostoa lanata cristate  (Kunth) Britton & Rose 1920 (Peruvian Old Man)
This cactus has a columnar stem up to 20 ft tall with 20 - 25 ribs under woolly white hairs of variable length. The white hairs conceal sharp spines. Mature plants develop a pseudocephalium of brown-grey spines and wool on one side of the stem, from which small, white nocturnal flowers are produced. The spherical purple-red fruit one inch in diameter are sweet and juicy and contain small, shiny black seeds.
 
Native to Northern Peru and Southern Ecuador, growing mainly on Western slopes of the mountains at elevations of 4000 - 7000 ft.
This is the commonest species in cultivation. The plant shown here has a normal offset despite a cristate main stem that may be developing some normal growth. The side shoots are growing faster than the cristate head.

Ferocactus acanthodes  Britton & Rose 1922 (Compass Barrel Cactus)
Syn. Ferocactus cylindraceus  (Engelmann) Orcutt 1926
Name: Greek akanthodes = spiny 
A usually solitary columnar (8ft) cactus with prominent ribs obscured by four straight to curving pink to grey central spines and 8 to 28 lighter colored fine radial spines from each areole. One of the central spines is usually especially long (5in) and curves down. Flowers are greenish yellow, occasionally tinged with red and are followed by yellow fruit.
 
This cactus is native to the Eastern Mojave Desert and Western Sonoran Desert of Southern California, Nevada, Arizona, and Utah, Baja California, and the Mexican state of Sonora state. Plants may lean towards the South-West and in some cases fall over and continue to grow along the ground.

Ferocactus glaucescens  (de Candole) Britton & Rose 1922 (Blue Barrel Cactus)
Name: Latin glaucescens = glaucous 
This strongly-ribbed cactus can remain solitarry or with maturity form large clumps by basal offsetting. Spination seems variable from 6 - 7 radial and 1 central spine, to no spines (forma nuda). The yellow, funnel-shaped flowers are quite long lasting. Petal margins are irregular.
 
Native to the Mexican state of Hildago, growing among limestone rocks in juniper woodland at up to 4000ft above sea level.

Ferocactus haematacanthus  (Monville ex Salm-Dyck) Bravo ex Backeberg & Knuth 1935 (Texas Barrel)
Name: Latin hamatus + Greek akanthos = hooked spine 
This is the only barrel cactus native to Texas, reaching a height of about 4 ft, although usually seen at a much smaller size. The solitary globular green body has 13 - 17 ribs with closely-spaced areoles bearing 6 - 7 radial spines and 4 long hooked central spines.
 
Native to the Chihuahuan Desert of South-Western Texas, New Mexico and North-Western Mexican states of Puebla and Veracruz, usually on limestone soils.
Photo: Black Gap Wildlife Management Area, Texas.

Ferocactus hystrix  (De Candole) G.E. Lindsay 1955 (Electrode Cactus, Candy Barrel Cactus, Mexican Barrel Cactus )
Syn. Echinocactus electracanthus   de Candole 1828
Name: Latin electra + Greek akanthos = yellow (amber) spines, hystrix = spiny  
A solitary globular barrel cactus growing up to 4ft tall with a green ribbed (20 - 40) body, a wooly central top and 10 - 12 amber-yellow spines with a reddish base arising from wooly areoles. There are 1 - 4 stout central spines and 6 - 9 less stout radial spines.
 
Native to arid highlands of central Mexico where it is common in forests and scrub at 4000 - 8500 ft above sea level. This cactus is used in the candy industry. The flower buds and fruits are also eaten and the fruits are fermented to an alcoholic drink.

Ferocactus pilosus  (Galeotti ex Salm-Dyck) Werdermann 1933 (Mexican Lime Cactus, Mexican Fire Barrel)
Name: Latin pilosus = shaggy 
This large, solitary or clumping barrel cactus has a strongly ribbed, bright green body contrasting with strong red central spines. Radial spines are either absent or reduced to white fibres which on some plants may be plentiful. Becoming columnar (8ft) with age, this cactus may offset low down to form a group of short columns. Flowers are red to yellow with a scaly ovary and are followed by yellow fruit.
 
Native to limestone soils over a wide range in the Mexican states of Nuevo León, San Luis Potosí, Coahuila and Zacatecas.

Ferocactus schwarzii  Lindsey 1955
Named for: Friedrich (Fritz) Schwarz (1900 - 1988) German botanist who first collected this species. 
This large, solitary barrel cactus becoming a short column (3ft) with age, has a deeply ribbed, bright green body. Areoles along the ribs have some white felting and 4 - 5 needle-like yellow central spines which become fewer as the plant matures. Flowers are yellow with a scaly ovary and are followed by brownish fruit.
 
Native to the central Mexican state of Sinaloa.

Ferocactus wislizenii  (Engelmann) Britton & Rose (Candy Barrel Cactus, Fishhook Barrel Cactus)
Named for: Friedrich Adolph Wislizenus (1810-1889) German-born American physician, explorer and botanist. 
This large, solitary barrel cactus has a strongly ribbed (20 - 28), green body largely obscured by 3 - 4 strong red central spines at least one of which is flattened and hooked and 12 - 20 fine white radial spines. Spination is strongest in full sun and weaker in the shade and in cultivation. This species becomes a short column (6ft) with age, typically leaning towards the South-West. Flowers in late Spring to early Autumn are orange-red with a scaly ovary and are followed by edible yellow fruit.
 
Native to the Sonoran and Chihuahuan deserts of South-Eastern Arizona, East to Southern New Mexico and East Texas and Northern Mexico. Locally prolific in some areas. Chunks of this cactus are preserved with sugar as a sweetmeat. The seeds have been used by indians to make flour and the spines as fish hooks.

Gymnocalycium achirasense  H.Till & Schatzl 1987
Syn. Gymnocalycium monvillei  Pfeiffer ex Britton & Rose subsp. achirasense (H.Till & Schatzl) H.Till 1993

 
Native to Northern Argentina.
Photo: Holly Gate Cactus Nursery reference collection

Gymnocalycium friedrichii (Werdermann) Pazout 1964 (invalid name)
Syn. Gymnocalycium mihanovichii  Frič ex Gürke) Britton & Rose 1922

 
Native to Bolivia, Paraguay and Argentina.

Gymnocalycium gibbosum   (Haworth) Pfeiffer ex Mittler 1844
This is the type species of the genus Gymnocalycium.
 
Native to Argentina.

Gymnocalycium lafeldense  Vaupel 1924
Syn. Gymnocalycium bruchii   (Spegazzini) Hosseus 1926

 
Native to Western Argentina.

Gymnocalycium monvillei ssp. horridispinum  (G.Frank ex H.Till) H.Till 1993
Syn. Gymnocalycium horridispinum  G.Frank ex H.Till 1987
Named for: M. Chevalier de Monville (1794 - 1863) French botanist 

 
Native to Argentina.

Gymnocalycium parvulum  Spegazzini 1925
Name: Latin parvulum = very small 
This is a small plant whose greenish-brown body has 9 - 13 ribs with areoles producing 5 - 7 radial spines and no central spines. The funnel-shaped flowers are white with a reddish-purple throat.
 
Native to Argentina.

Gymnocalycium pflanzii  (Vaupel) Werdermann 1935
Named for: Karl Pflanz (1872-1925) German botanist and plant collector. 

 
Native to Bolivia, Paraguay and Argentina.

Gymnocalycium saglionis  (Cels) Britton & Rose1922
Named for: Joseph Saglio, French cactus collector 
This solitary barrel cactus has a dark green body up to 3ft tall and with 10-30 ribs. Areoles produce 10 - 15 red to black radial spines recurved towards the body and 1 - 3 curved central spines. Pale pink to white flowers are produced in a ring around the top of the plant thoughout the growing season. the globular red fruit are spontaneously dehiscent, revealing many dark brown seeds.
 
Native to Northern Argentina.

Hylocereus costaricensis  (F.A.C. Weber) Britton & Rose 1909 (Costa Rica Night Blooming Cactus)
Syn. Hylocereus polyrhizus - garden origin
Name: Native to Costa Rica 
This cactus has thick, green angular stems with well-spaced areoles along the wavy margins but with few spines. The stems are usually rooted in the ground and scramble through bushes and trees. The large perfumed cream-coloured flowers open mainly at night and are followed by red fruit with purple pulp and many tiny black seeds.
 
Native to South America and the Caribbean, Costa Rica, Nicaragua to Peru

Lepismium ianthothele  (Barthlott & Rauh) Barthlott 1987
Syn: Pfeiffera ianthothele  F.A.C. Weber (1898)
Name: Greek ianthos = violet + thele = warts, referring to the fruits. 
This sprawling epiphyte has soft, 3 - 5 angled stems with well-spaced areoles funished with 6 - 7 spines. The white flowers produced in early Summer are followed by purple-pink berries.
 
Native to South-East Bolivia.

Lepismium miyagawae  (Barthlott & Rauh) Barthlott 1987
Syn. Pfeiffera miyagawae Barthlott & Rauh 2002
Named for: Mario Miyagawa who collected this species. 
This sprawling epiphyte has soft, 3 - 5 angled stems with well-spaced areoles producing white wool, bristles and soft white spines. The orange flowers produced in the Spring are quite big for the genus and have a spiny ovary and pericarp. Fruit are white.
 
Known from 2 collections in Dept. Cochabamba, Bolivia.

Lophophora williamsii  (Lemaire ex Salm-Dyck) J.M. Coulter 1894
Named for: Sir. C.H. Williams, British Ambassador to the state of Bahia, Brazil 
The plant body is a blue-gray button divided into ribs by incised lines and with tubercles marked by tufts of wool. Small pink flowers are produced freely from the centre of the body. The thick tap-root is a little sensitive to excessive watering.
 
Photos: West of Terlingua, Texas.

Mammillaria bocensis  Craig 1945
Name: found near to Las Bocas, Sonora, Mexico 
The globose to cylindrical dark green body mostly remains solitary but old plants may cluster. Each tubercle produces 6 - 8 radial spines with reddish-brown tips and a single central spine. Flowers are greenish-yellow to pale pink with a darker brownish stripe along the petals and a bright green style. They are followed by club-shaped red fruit.
 
Native to the Mexican states of Sonora, Sinaloa, Jalisco and Nayarit, growing in coastal salty flats and scrub and up to 300ft above sea level.

Mammillaria bocasana  Poselger 1853 (Powder Puff Cactus)
Name: found in Sierra de Bocas Mountain range, San Luis Potosí, Mexico 
This popular fast-growing, clumping cactus has bluish green tuberculate stems that are mostly obscured by clusters of long silky white hairs and a single (rarely two) long reddish-brown fish-hook spine from each tubercle. Flowers may be pink or yellow and are followed by cylindrical pink fruit. There are several selected cultivars with differing amounts of hairs and flower colour.
 
Native to the central Mexican states of San Luis Potosi, Queretaro and Zacatecas at altitudes of up to 7500 ft above sea level. This is a very easy freely-flowering cactus to grow and if potted on will soon form a nice clump. It is best watered from below as the silky white hairs become matted otherwise.
There is a cristate form of Mammillaria bocasana which continues to flower nicely with pink flowers along the crest. Mammillaria bocasana cv. Fred is a monstrose cultivar that over time has diversified into several clones with weird shapes.

Mammillaria candida  Scheidweiler 1838 (Snowball cactus)
Syn. Mammilloydia candida  (Scheidweiler) Buxbaum 1951
Syn. Neomammillaria candida (Scheidweiler) Britton & Rose 1923
Name: Latin candida = white 
This globular cactus, becoming cylindrical with age, is covered with fine white hair and many short, white or brown spines. Each tubercle can produce as many as 120 radial spines. Old plants can form large clumps. The flowers are pale yellow to pale pink with a darker stripe along the middle of the petals.
 
Native to the Mexican states of Coahuila, Nuevo León, San Luis Potosí and Tamaulipas, growing on limestone soils and rocks at altitudes of 1,600 - 8,200 ft above sea level. In cultivation, ground limestone can be added to the soil.

Mammillaria dixanthocentron  Backeberg 1963
Name: Greek di = two + xanthos = yellow + kentron = center, referring to the two central spines 
The globose dark green body is obscured by 19 - 20 white radial and 2 -4 white to brown central spines with dark tips. Some cultivated forms have been selected for exceptional length of the central spines and different spine colours. The small flowers are pink to red and are followed by orange club-shaped fruit.
 
Native to the Mexican states of Oaxaca and Puebla at altitudes of up to 6500 ft in dry deciduous forests and clinging to cracks in rocks.

Mammillaria elongata  De Candole 1828 (gold lace cactus, ladyfinger cactus)
Name: Latin longus = long, referring to elongated stems 
The cylindrical stems have spirally-arranged conical tubercles with 14 - 25 golden radial spines and few or no central spines. The interlocking spines form a mesh covering the stems. Many small cream-coloured flowers (sometimes flushed with pink) are produced in the Spring and are followed by cylindrical red fruit. As the stems elongate they become prostrate. Roots are fibrous.
 
Native to the central Mexican states of Hildago, Guanajuato, and Queretaro. Named cultivars have been selected on the basis of different spine colours from dark brown to white, and a cristate form is sometimes seen.

Mammillaria formosa  Galeotti ex Scheidweiler 1838
Name: Latin formosa = well designed 
The globose green bodies have prominent tubercles with 2 - 6 central spines and very fine radial spines. Axils are woolly, especially around flowers. Flowers are pale pink with a darker stripe along the middle of the petals. By dichotomous division of plant bodies and offsetting, this species can form large clumps.
 
Native to the Mexican states of Coahuila, Aguascalientes, Guanajuato, Zacatecas, Tamaulipas, Nuevo León and San Luis Potosí, Mexico.

Mammillaria glassii R.A. Foster 1968
Named for: Charles Edward Glass (1934-1968) American horticulturalist & plant collector 
This small mat-forming cactus offsets freely to form fluffy white clumps. The short globose stems have areoles that produce 50 - 60 hair-like radial spines and 1 - 4 hooked or straight central spines. The axils also produce 10- 20 white bristles. The small, funnel-shaped flowers are pale yellow to pale pink and are followed by bright red, oval fruit filled with black seeds.
 
Native to the Sierra Madre Oriental mountain range across the Mexican states of Coahuila, Nuevo León and Tamaulipas, growing at altitudes of 4750 - 7400 ft above sea level. If kept dry, will tolerate light frost.

Mammillaria gracilis  Pfeiffer 1838
Syn. Mammillaria vetula subsp. gracilis (Pfeiffer) D.R. Hunt 1997
Small (1 - 2 in long) cylindrical green bodies are covered with white spines with 11 - 16 radial spines and 0 - 5 central spines from each areole, with centrals especially on mature stems. The stems offset freely along their length. Offsets detach very easily, but every one will root and form a new plant. The small pale yellow flowers have a darker mid-stripe and are followed by pink fruit.
 
Native to the Mexican states of Hilalgo and Queretaro,growing at up to 6000 ft above sea level. This cactus certainly tolerates some frost if dry, but not cold-wet conditions.
Various selected spine variants are in cultivation e.g. "Arizona Snowflake / Snowcap".

Mammillaria gracilis, possibly the cultivar "Arizona Snowflake / Snowcap"
dyed purple and marketed under the trade name Kosmic Kaktus.
A range of other colours are available. New growth will have the gleaming
white spines of the original plant so if you buy one of each colour, those
that grow will eventually all look the same.
 
Photo: Andrea Hüper, 2014.

Mammillaria grusonii  Runge 1889
Named for: Hermann August Jacques Gruson (1821 - 1895) German engineer & cactus collector 

 
Native to the Mexican states of Coahuila and Durango.
Photo: Holly Gate Cactus Nursery reference collection

Mammillaria haageana  Pfeiffer 1836 (Mexican Pincushion Cactus)
Named for: Friedrich Adolph Haage de Erfurt (1796 - 1866) German botanist 
This is a solitary or occasionally clumping globose cactus. Old plants may produce basal offsets. The axils produce abundant wool. Tubercles have 16 - 18 fine white radial spines and 1 - 2 stout grey-brown straight central spines. Flowers are pink to magenta-pink with a darker midstripe, produced in a ring around the top of the plant.
 
Native to a wide range in the Mexican states of Veracruz, Puebla, México, Morelos, Oaxaca and Ciudad de México.

Mammillaria hahniana  Werdermann 1929 (Old Lady Cactus)
Named for: Adolf Hahn (b. 1954) German cactus collector from Berlin 
The axils of some clones produce white hairs up to 1.5 in long that cover the globose to cylindrical green plant body. Nurserymen tend to propagate extreme forms but this is unreprentative of the wild population. The areoles have 20 - 30 hair-like radial spines and 1 - 4 short white central spines with darker brown tips. Flowers are in shades of pink.
 
Native to the central Mexican states of Guanajuato, Querétaro Arteaga and Tamaulipas.
Photo: Holly Gate Cactus Nursery reference collection

Mammillaria heyderi  Muehlenpfordt 1848
Named for: Privy Councellor Eduard Heyder (1808-1884) German cactus expert from Berlin 

 
Native to Oklahoma, New Mexico and Texas USA and the Mexican states of Tamaulipas, Nuevo León, Coahuila, Durango, Sonora, San Luis Potosí and Veracruz.

Mammillaria heyderi subsp. meiacantha  (Engelmann) D.R. Hunt 1997

Mammillaria lasiacantha  Engelmann 1856
Name: Greek lasios = hairy + akanthos = spine 
This mature Mammillaria lasiacantha is only about 1.5in in diameter. The plant body is entirely obscured by a lacy mat of white spines. Areoles produce 40 - 80 smooth to plumose radial spines held against the plant body and no central spines. Small cream flowers, whose petals have a green, yellow, pink to pale purple mid-stripe, are produced in late Winter to early Spring.
 
Native to Chihuahuan desert limestone soils in Texas and New Mexico and the Mexican states of Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora and Zacateca.
Photo: Limestone cliffs above and to the South of Terlingua.

Mammillaria longimamma  A.P. de Candolle 1828
Syn. Dolichothele uberiformis  (Zuccarini) Britton & Rose 1923
Name: Latin longimamma = long nipple 
Thick taproots support a light green stem with long, soft tubercles. The main stem forms a clump by basal offsetting. Areoles produce 8 - 10 long pale brownish radial spines and a single long straight central spine. Flowers, produced from the axils, are yellow with a yellow stigma and relatively large and are followed by yellowish fruit.
 
Native to the Mexican states of Hidalgo and Querétaro. In cultivation a deep pot is advisable to accommodate the tap root and a very free-draining potting mix and careful watering are advisable. A single whole tubercle is sufficient to propagate this cactus.

Mammillaria microhelia  Werdermann 1930
The short (6 in) cylindrical body is hidden by 30 -50 fine white radial spines with a pectinate arrangement and 1 - 4 brown central spines from each tubercle. Plants may be solitary or clump up by basal offsetting. Flowers are pale yellow or pink.
 
Native to a limited range in the Mexican state of Querétaro, growing among volcanic rocks. Easy in cultivation.

Mammillaria perezdelarosae  H. Bravo & L. Scheinvar 1985
Syn. Mammillaria bombycina ssp. perezdelarosae  (Bravo & Scheinvar) D.R. Hunt 1997
Named for: Jorge Perez de la Rosa (b. 1955) Mexican forestry specialist, Secretary of Botanical Institute of University of Guadalajara. 
This slow-growing solitary or clumping cactus has globose tuberculate stems, becoming cylindrical. The areoles produce 30 - 60 very fine white radial spines in a pectinate arrangement and 1 -2 reddish-brown, hooked central spines. Flowers are greenish white to pale pink with a darker mid-stripe, followed by red fruit containing dark brown seeds.
 
Native to the Mexican states of Jalisco and Aguascalientes.

Mammillaria pottsii  

 
Native to
Photo: Limestone cliffs above and to South of Terlingua.

Mammillaria prolifera  (Miller) Haworth 1812 (Texas Nipple Cactus)

 
Widely distributed from Texas into the Mexican states of Coahuila, Nuevo León, Querétaro, San Luis Potosí & Tamaulipas. Also in Cuba, Dominican Republic & Haiti.
Photo: cultivated plant.

Mammillaria schiedeana  Ehrenberg 1838
This small cactus forms multiheaded clumps up to 2 in high. The globose to cylindrical stems are hidden by a mesh of pale yellow spines. Flowers are white to pale pink, sometimes with a darker mid-stripe and are followed by bright red cylindrical fruits. Roots are fleshy so need good drainage.
 
Native to the Mexican states of Hidalgo, Queretaro de Arteaga, San Luis Potosi and Tamaulipas. Likes a limestone soil.

Mammillaria surculosa  Bödeker 1931
Syn. Dolichnthele surculosa   (Bödeker) Backeberg 1951
This dwarf globular dark-green cactus soon clumps up to form a mat. The areoles produce 15 radial white spines and 1 - 2 golden hooked central spines. There is a fleshy taproot. The small funnel-shaped yellow flowers are lightly perfumed and are followed by brownish fruit.
 
A rare plant, native to the Mexican states of San Luis Potosí and Tamaulipas growing at 9800 - 10500 ft above sea level. It is widely propagated in the horticultural trade.

Mammillaria tetrancistra  Engelmann 1852 (California Fishhook Cactus)
This small cactus has a globular to cylindrical stem up to 6 in tall, largely obscured by the spines. The areoles have 3-4 dark-brown hooked central spines and 20 - 60 white radial spines. Flowers are in shades of pink and are followed by shiny red fruit full of black seeds.
 
Native to the Mojave and Sonoran Deserts of the South-Western USA into Mexico, including Southern Arizona, South-East California, Southern Nevada and South-East Utah.
Photo: Death Valley National Park.

Mammillaria varieaculeata  Buchenau 1966
This cactus clumps up by dichotomous division of heads and also by basal offseting. Spine length is variable within the widl population. Axils produce 10 - 25 white bristles, 17 - 24 yellowish-brown radial spines and 1 - 5 darler brown central spines. The small flowers are red and are followed by scarlet club-shaped fruit.
 
Native to the southern part of the Mexican state of Puebla near its border with Oaxaca.

Mammillaria wiesingeri ssp. apamensis  (W. Reppenhagen) D.R. Hunt 1997
These small globose cacti are solitary or clumping with age. Tubercles produce 13 - 16 yellowish radial spines and 1 - 2 darker central spines. Flowers are pink.
 
Native to the Mexican state of Hidalgo.

Matucana aureiflora  F. Ritter 1965
Syn. Borzicactus aureiflorus (Ritter) Donald 1971
Name: aureiflora = golden flowers 
This flattened globular cactus has a glossy green stem with pectinate spines supported by a tap root. The spination varies from a robust cage-like structure to very minimal spination allowing the sculptural form of the plant body to be appreciated. The areole of young plants produces a vestigial leaf scale. The golden-yellow flowers remain open day and night.
 
Native to Peru, growing in the valleys of the Andes around 9500 ft above sea level.

Matucana intertexta  F. Ritter 1963
Name: Latin intertextus = interwoven, referring to the spines 
This small globular cactus has a dark green body patterened by rounded tubercles with curved black radial spines and 1 - 4 central spines. Plants are usually solitary but may produce occasional basal offsets.
 
Native to the Cajamarca region of Peru.

Matucana madisoniorum   (Hutchison) G. D. Rowley 1971
Syn. Submatucana madisoniorum (Hutchison) Backeberg 1966,  Borzicactus madisoniorum Hutchison 1963.
Named for: Mr. & Mrs. Madison who funded the expedition that found the plant. 
This flattened globular to elongated cactus is usually solitary but may offset with age. The stem has a matt blue-green surface with prominent rounded ribs bearing slightly wooly areoles that tend to lose most of their spines as the plant matures. Juvenile plants have a dense array of curving spines. Flowers are bright orange-red with a long floral tube, produced throughout the Summer. A form 'alba' with a white flower is known.
 
Native to Amazonas region of Peru, growing at low altitudes near the edge of the Amazon rain-forest.

Matucana weberbaueri  (Vaupel) Backeberg 1939
Syn. Cleistocactus sepium (Kunth) A.Weber 1904
Named for: August Weberbauer, Prussian (German) biologist 
A usually-solitary globular cactus whose areoles produce 25 - 30 long stright yellow-brown spines. Flowers are yellow to orange. In cultivation may offset with maturity.
 
Native to the Peruvian region of Amazonas, around 6800 ft above sea level.

Melocactus bahiensis  (Britton & Rose) Luetzelburg 1923
Name: refers to presence in state of Bahia, Brazil 
Flowers are pink to magenta, followed by reddish fruit.
 
Native to Brazil.
Photographed at RBG Kew.

Melocactus ernestii  Vaupel 1920
Named for: Ernst H.G. Ule (1854 - 1915) German botanist and explorer of Brazil 
This large Melocactus has the longest spines in the genus. Flowers are pink to red.
 
Native to Brazil.
Photographed at RBG Kew.

Melocactus peruvianus  Vaupel 1913
Name: refers to presence in Peru 
Native to Ecuador and Peru.
Photographed at RBG Kew.

Melocactus zehntneri  (Britton & Rose) Luetzelburg 1923
Named for: Leo Zehntner (1864 - 1961) Swiss entomologist & botanist 
Native to North-Eastern Brazil.
Photographed at RBG Kew.

Myrtillocactus cochal  (Orcutt) Britton & Rose 1909 (Candelabra Cactus)
Name: 'cochal' is the common name for this plant 
Myrtillocactus cochal grows as dense shrubs up to 12 ft tall with a short woody trunk bearing many six to eight-ribbed branches. Areoles have a long central spine with five shorter radial spines. The small flowers are greenish-white and followed by edible maroon berries.
 
Native to Baja California. Photographed at RBG Kew.

Myrtillocactus geometrizans  (von Martius) Console 1897   (Bilberry Cactus, fruit = Garambullo)
Name: Latin geometricus = geometric, referring to the architectural stems 
The robust nature of Myrtillocactus geometrizans makes it suitable for grafting stock, although it is not cold-hardy. Each areole can produce several brownish buds that open into greenish-white, waxy flowers less than 1 in long, and with short floral tubes. Flowers are followed by edible, blue berries which are harvested for sale in Mexican markets.
 
Native to Mexico including Baja California to Guatemala and widely cultivated. A cristate form is commonly seen in cultivation. Photographed at RBG Kew.

Neolloydia conoidea  Britton & Rose 1922 (cone catus, Chihuahuan beehive)
Name: Greek konos = cone + oideos = a form or type of 
The unbranched ovate to conical body can reach 9in tall and 3in diameter. Tubercles are grooved. Flowers are pink to magenta with a white outer surface and a scaly floral tube.
 
Widely distributed in Western Texas and the Mexican states of Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, and Zacatecas, typically growing on limestone and often locally abundant.

Neolloydia intertexta  (Engelmann) L.D. Benson 1969   -   See Echinomastus intertextus

Oreocereus celsianus  (Salm-Dyck) A.Berger ex Riccobono (Old Man of the Mountains)
Named for: Jacques Philippe Martin Cels (1740 - 1806) French botanist 
This columnar (10 ft) cactus has a body with 10 - 25 ribs, covered in white hairs through whic protrude sharp brown spines. Mature plants clump up by basal offsetting. The tubular red flowers are attractive to humming birds.
 
Native to Andes mountains of Argentina, Bolivia and Peru.

Oreocereus doelzianus  (Backeberg) Borg 1937 ()
Syn. Morawetzia doelziana Backeberg 1936, Borzicactus doelzianus (Backeberg) Kimnach 1960
Named for: Bruno Dölz (1906 - 1945) German cactophile and president of Deutsche Kakteen Gesellschaft. 
The 3in diameter stems have 10 - 11 ribs and grow up to 3ft tall. Brownish spines are hidden amonmg many hairs that protect against cold and condense moisture from fogs. As stems mature they develop an apical pseudocephalium of wool and long bristles, which was used to justify separation into the genus Morawetzia. The tubular scarlet flowers with a hairy flower tube appear at the apex of the stems, opening at their tips to display a ruff of pointed petals and yellow stamens.
 
Native to high valleys among the Andes mountains of Peru, growing at elevations of 8000 - 9800 ft above sea level on Eastern slopes where they will get the morning sun. At such altitudes they experience freezing conditions and are cold hardy under very dry conditions, but otherwise very sensitive to moisture.

Oreocereus trollii  Kupper 1929 (Old Man of the Mountain / Andes)
Syn. Borzicactus celsianus var. trollii (Kupper) G.D.Rowley 1986
Named for: Carl Troll (1899 - 1975) German botanist & geographer 
This short (2 ft) columnar cactus has a ribbed body that is densely coated in matted white hairs with protruding brown spines. Mature plants clump up by basal offsetting. The tubular flowers are violet-red to pink.
 
Native to Andes mountains of Northern Argentina and Southern Bolivia growing at elevations of up to 14,000 ft above sea level. Popular in cultivation but needs careful watering to avoid the white hairs wicking up salts and becoming dicoloured. Avoid watering during cold weather and Winter.

Pachycereus pringlei  (S. Watson) Britton & Rose 1909 (Cardón, Mexican Giant Cardón)
Named for: Cyrus Guernsey Pringle (1838 - 1911) American botanist, explorer & plant breeder.
Common name: Cardón from the Spanish cardo = thistle 
This is one of the largest cacti in the world, whose trunk with 11 - 17 ribs typically grows over 30ft tall and 3 - 4ft in diameter. Specimens have been recorded as growing 63ft tall during a lifespan of hundreds of years. Small specimens, typically seen in glass-house collections, are very spiny with 20 - 30 gray spines per areole but the spines are mostly lost as the trunk grows above the reach of herbivores. Mature specimens have side branches to the trunk forming a candelabra of branches. White flowers are produced in the Spring followd by tan coloured, spiny fruits.
 
Native to the Mexican states of Sonora and Baja California. Symbiotic nitrogen-fixing micro-organisms on the roots allow this cactus to grow without soil, even on bare rock. The spiny fruits contain edible pulp. This cactus produces alkaloids and a slice was traditionally used to treat rheumatism and aches.

Pachycereus schottii  D.R. Hunt 1987 (Senita Cactus)
Syn. Lophocereus schottii Britton & Rose 1909
Mature flowering stems develop a pseudocephalium of long, hairlike, grey spines towards their ends.
Photograph: Organ Pipe Monument Az.

Parodia magnifica   (Ritter) F. H. Brandt 1982
The spherical to columnar blue-green plant body has dense yellow to brown spines and hairs along its ribs. Old plants clump up by offsetting. Pale yellow flowers are produced at the apex of the cactus.
 
Native to Southern Brazil, Paraguay, Uruguay and Argentina.
Photo: a very old clump at RBG Kew.

Parodia scopa  (Sprengel) N. P. Taylor 1987
Syn. Notocactus scopa  (Sprengel) A. Berger 1929
Name: Latin scopa = broom, referring to the dense spines 
A globular cactus becoming cylindrical with age. The spiny, wooly crown produces yellow flowers in early Summer.
 
Native to Southern Brazil and Uruguay.

Notocactus succineus  F. Ritter 1970 (Silver Ball Cactus)
Syn. Parodia scopa subsp. succinea (F. Ritter) Hofacker & P.J. Braun 1998

Parodia warasii   (F. Ritter) F.H. Brandt 1982
Named for: Eddie Waras, Bromeliad & Orchid collector, nurseryman from Sao Paulo, Brazil 
This globular to short columnar cactus is similar to P. magnifica but with a bright green stem offsetting the golden spines along the ribs. Stems may offset or remain solitary. Golden yellow flowers are produced around the crown of the plant in the Summer.
 
Native to the Brazilian state of Rio Grande do Sul .
Photograph: bedded out for the Summer at RBG Kew.

Wilcoxia viperina
Syn. Peniocereus viperinus

Rebutia albiflora  Ritter & Buining 1963
Named for: Latin albi = white + flora = flower 
This clumping cactus has small globose stems covered with soft radial spines. The relatively large (1 in diameter) flowers are white to pinkish-white with an externally pink flower tube and are followed by dry red fruits.
 
Native to South-East Bolivia.

Rebutia caineana  Cárdenas 1966
Syn. Rebutia breviflora  (Backeberg) D.R. Hunt 2002  Syn. Sulcorebutia breviflora Backeberg 1966
This globular cactus has a long, thick tuberous root and clumps up by basal offsetting. Yellow funnel-shaped flowers are produced freely on mature stems.
 
Native to Cochabamba, Potosi, Bolivia, where it grows among sandstone rocks at an altitude of 6500 - 9800 ft above sea level. The tap root requires careful watering or it may rot.

Rebutia heliosa  Rausch 1970
Name: Greek heliosa = of the sun 
This miniature cactus has tiny heads of up to an inch in diameter, clumping up to form a low mound. The stems are covered in short silvery pectinate spines in a spiral formation. There is a fleshy taproot under the cactus.
 
Native to high mountains of Bolivia, growing at 8000 - 9800 ft above sea level.

Rebutia heliosa x albiflora
An attractive, free-flowering hybrid that quickly forms a mat of small, globular plant bodies. As with many hybrids, some variation is seen in the flower colours and selected forms have been propagated with flower colours from pale pink to peach.

Rebutia neocummingii (Backeberg) D.R. Hunt 1987 see:
Weingartia neocummingii

Rebutia pygmaea  (R.E. Fries) Britton & Rose 1922
Syn. Lobivia pygmaea (R.E. Fries) Backeberg 1935
This small clumping cactus has around 60 synonyms, reflecting variability over its large range.
 
Native to Bolivia and Argentina.

Rebutia spegazziniana  Backeberg 1933
Syn. Rebutia tarijensis  Ritter 1977

Rebutia steinbachii  Werderman 1931
Syn. Sulcorebutia steinbachii  (Werderman) Backeberg 1951

Rhipsalis baccifera (J.S. Mueller) Stearn 1939 (Mistletoe Cactus)
This is a variable species with a wider natural distribution than any other cactus. South American plants are diploid but those from Mesoamerica, the Caribbean and elsewhere are tetraploid. R. baccifera is found also in tropical rainforests of Africa, Madagascar, Seychelles, Mauritius, Reunion, India and Ceylon. As R. baccifera is not ancestral to Cactaceae and unlikely to have evolved before separation of the continents, this pandemic distribution may reflect transport by migratory birds or humans, perhaps for the sweet berries.

Rhipsalis baccifera ssp. mauritiana  (De Candolle) Barthlott 1987 (Mistletoe Cactus)
This sub-species from the Indian Ocean area is tetraploid with 44 chromosomes. The white berries are edible and larger than those of the diploid sub-species.

Above: Rhipsalis cereoides  (Backeberg & Voll) Backeberg 1937
This cactus grows mainly as an epiphyte. The three (occasionally four) -cornered stems are joined end to end, often branching at the stem joints. Small areoles with a few bristles can be found along the stems. The small white flowers appear from the areoles in groups and are followed by red translucent fruit.
 
Native to rainforests of Brazil.

Rhipsalis mesembryanthemoides  Haworth 1821 (Clumpy Mistletoe Cactus )
Name: mesembryanthemoides = appearance similar to genus Mesembranthemum 
The branching stems of this epiphyte produce many half-inch long side-shoots packed together along the main stem. Areoles have fine white hairs and some aerial roots. White flowers are followed by oblong white fruit.
 
Native to Brazil and not uncommon in cultivation.

Rhipsalis neves-armondii  K.Schumann 1890
Named for: Amaro Ferreira das Neves Armond, Director of the Brazilian National Museum (1892 - 1893). 
This epiphyte has narrow angular to rounded, frequently-branching stems forming a clump. The stems have a few areoles along their length, but no spines. Some wool is produced at the base of flowers and fruit. Flowers are white with a yellow or pink center followed by small red berries.
 
Native to Brazil, typically hanging in clusters from trees. As with most under-storey epiphytes, partial shade is better than full sun. Occasional aerial roots are produced from areoles and the plant may be grown as an epiphyte as illustrated, if sprayed regularly.

Rhipsalis pilocarpa   Lofgren 1903
Name: Latin pilus = hairy + carpus = fruit 
The long thin branching stems are distinctively covered in fine hairs growing from otherwise spineless areoles. In mid-Winter, bell-like white flowers are produced at the ends of the stems. The interiors of the flower tunes may be tinged with pink. Flowers are followed by red berries whose surface has areoles bearing tufts of hairs.
 
Native to Brazil. This is an ideal plant for a shady corner of the greenhouse or conservatory.

Schlumbergera truncata  (Haworth) Moran 1953
Syn. Zygocactus truncatus  (Haworth) K. Schumann 1890 (Christmas cactus)
The traditional "Christmas Cactus" is a hybrid Schlumbergera x buckleyi with a magenta flower. The wild form of Schlumbergera truncata in Brazil has a red flower.
 
A range of hybrids with flowers in other colours have become available recently. However, many are temperature-sensitive and revert to pink unless the buds develop in warm conditions, although bud initiation occurs best in cool temperatures.

Sclerocactus papyracanthus (Engelmann) N.P. Taylor 1987 (Paper-Spined Cactus)
Syn. Toumeya papyracantha  Britton & Rose 1922
 
Photograph: gypsum salt flats in front of Guadalupe Mountains, Texas.

Sclerocactus parviflorus  Clover & Jotter 1941 (Devil's Claw Cactus)
Name: Latin parviflorus = small flowers, perhaps not entirely appropriate 

 
Extreme left: Robin Howard, Cheyenne Mountain State Park, Colorado. June 2008
Left: Robin Howard, Colorado Springs, Colorado. June 2008

Sclerocactus polyancistrus  (Engelmann & Bigelow) Britton & Rose 1922
Syn. Pediocactus polyancistrus (Engelmann & J.M. Bigelow) Arp 1972
This species, clumping with age, has a cylindrical stem up to 10 in tall, obscured by dense spination. Areoles have reddish or whiteish long central spines with hooked tips and several white radial spines. The perfumed flowers are pink and followed by scaly fleshy fruit.
 
Native to the Mojave Desert of Eastern California and Southern Nevada, often on limestone soils.
Photo: Death Valley National Park.

Sclerocactus scheeri  (Salm-Dyck) N.P. Taylor 1987
Syn. Ancistrocactus scheeri (Rose) Britton & Rose 1923
Named for: Friedrich Scheer (1792 - 1868) German botanist and cactus enthusiast. 
A fleshy tuberous taproot supports a usually-solitary, large globular cactus. Areoles have 13 - 28 radial spines and 3 -4 hooked central spines. Juvenile plants have only radial spines. Flowers are bright green to yellowish in early Spring.
 
Native to Texas and the Mexican states of Nuevo León and Tamaulipas. Indians used the central spines as fish hooks.
Photo: Amistad Recreation Area, Texas.

Sclerocactus uncinatus  (Galeotti) N.P. Taylor 1987 (Turk's Head Cactus)
Syn. Glandulicactus uncinatus  (Galeotti) Backeberg 1939

 
Photo: Black Gap Wildlife Management Area near Dog Canyon, Texas.

Selenicereus anthonyanus (Alexander) D.R. Hunt 1989 (Fish Bone Cactus)
Syn. Cryptocereus anthonyanus  Alexander 1950
Named for: Dr. Harold E. Anthony (1890 - 1970) American zoologist & paleontologist, first to flower this plant 
The notched stem may be an adaptation to the low light levels under the rainforest canopy, by increasing the area of the photosynthetic stem instead of producing leaves. The large fragrant flowers open for just one night.
 
Native to the rainforests of Chiapas, Oaxaca, Tabasco and Veracruz, Mexico.

Selenicereus grandiflorus  (Linnaeus) Britton & Rose 1909 (Queen of the Night)
Name: grandiflorus = large flowered 
The large fragrant white flowers open for less than one night.
 
Native to Cuba, Cayman Islands, Jamaica, Haiti, Puerto Rico, Mexico, Belize, Guatemala, Honduras and Nicaragua.

Selenicereus testudo  (Karwinsky ex Zuccarini) Buxbaum 1965 (Dog's Tail Cactus, Pitaya De Tortuga)
Syn. Deamia testudo Britton & Rose 1920
Name: testudo = large flowered 
This epiphytic cactus has long narrow angular stems that, as they mature become broad with 3 to 5 ribs furnished with sharp brown spines along their edges. The large fragrant white flowers may be open for several days and are followed by purple spiny fruit.
 
Native to dry rain forests of Belize, Costa Rica, Guatemala, Honduras, Mexico, and Nicaragua where it typically scrambles along tree branches or over rocks. In cultivation, it likes full sun.

Stenocactus crispatus  (de Candolle) A. Berger ex A. W. Hill 1933
Name: Latin crispus = with wavy margins, referring to the ribs. 

 
Widely distributed in the Mexican states of Guanajuato, Hidalgo, México Distrito Federal, México State, Oaxaca, Puebla, Querétaro, San Luis Potosí, Tamaulipas, Tlaxcala and Veracruz.
Photo: Holly Gate Cactus Nursery reference collection

Stenocactus multicostatus  (Hildmann ex K. Schumann) A. Berger 1929
Syn. Echinofossulocactus multicostatus (Hildmann ex K. Schumann) Britton et Rose 1922

 
Native to the Mexican states of Aguascalientes, Coahuila, Durango, Guanajuato, Jalisco, Nuevo León, Querétaro, San Luis Potosí, Tamaulipas and Zacatecas.
Photo: Holly Gate Cactus Nursery reference collection

Stenocactus ochoterenianus  Tiegel 1933
Name commonly seen as S. ochoterenaus.
This solitary cactus has a dark green body with up to 30 undulating ribs and yellowish wool around the apex. Flowers are white to purple with a darker central stripe.
 
Native to the Mexican states of Hidalgo, Queretaro and Guanajuato.

Stenocactus vaupelianus  (Werdermann) F. M. Knuth 1935
Syn. Echinofossulocactus vaupelianus  (Werdermann) H. C. Whitmore 1934
Named for: Friedrich Vaupel (1876 - 1927) German botanist 
This solitary species has a dark green body with around 35 undulate ribs. The body may be obscured by the strong spination, 10 - 25 radial and 1 - 4 central spines and white wool around the areoles. Flowers are pale yellow to pink, often with a darker mid-stripe.
 
Native to Mexian state of Hildago.

Stenocereus eruca  (Brandegee) Gibson & Horak 1978 (Creeping Devil)
Name: Latin eruca = caterpillar 
The Creeping Devil grows prostrate along the ground. It's 2in diameter spiny, cylindrical stem turns up a little at the growing point and roots where the body touches the ground. As the front of the plant grows, the rear end decays and crumbles away, so the effect is that the whole plant slowly moves forward. The stem branches near to the growing point. Eventually side branches detach and grow separately, as the decaying end reaches their branch point. The 4in long nocturnal flowers are pale yellow to pink followed by spiny fruit.
 
Native to sandy soils and coastal dunes in Baja California and Magdalena Island. This cactus is said to contain similar psychoactive alkaloids to peyote cactus and featured in native Indian ceremonies.

Stenocereus thurberi  (Engelmann) Buxbaum, 1961 (Organ Pipe Cactus, Pitaya Dulce, Ool)
Named for: George Thurber (1821 - 1890) American pharmacist, botanist and collector 
This cactus has up to twenty 6in diameter ribbed stems branching at or just above ground level and reaching 20ft or more tall. Stems may show annual growth rings. The shallow ribs have closely-spaced areoles with 9 - 10 short black radial spines. Mature stems produce 3 in long funnel-shaped white flowers which open at night to attract bats. Flowers are followed by large spiny fruit with red flesh that is compared favourably to watermelon.
 
Native to the Southern edge of Arizona, the Sonoran desert of Mexico and Baja California. The Organ Pipe National Monument in Arizona takes its name from this species. This cactus is not at all frost hardy which limits its distribution.

Thelocactus bicolor (Galeotti ex Pfeiffer) Britton & Rose 1922
This solitary, globular cactus has 8 ribs bearing rounded tubercles. Areoles have glands and produce 8 - 18 yellowish to reddish radial spines and 3 - 4 central yellowish to reddish spines. Magenta flowers with a red throat are produced from Spring to Autumn.
 
Native to a wide range from Texas to the central Mexican state of San Luis Potosí, growing on limestone or sandstone soils. Numerous varieties have been named from different parts of the distribution.

Thelocactus bicolor subsp. flavidispinus  (Backeberg) N.P. Taylor 1998 (Glory of Texas)
Name: flavidispinus = yellow spined 
A globular to short columnar cactus with 13 ribs with tubercles,mostly obscured by dense straw-coloured to red spination. Areoles have 12 - 20 radial spines and 3 - 4 central spines. Short-lived, large magenta flowers are produced in late Spring.
 
Native to Big Bend Country, Texas into Mexico, growing on acidic soils. Not difficult in cultivation, but tends to grow taller than in its habitat.

Thelocactus conothelos  (Regel & Klein bis) Backeberg & F.M. Knuth 1935
A globular cactus with four sub-species and a somewhat variable flower colour from white, yellow, red to purple.
 
Native to the Chihuahuan Desert in the Mexican states of Nuevo León, San Luis Potosí and Tamaulipas.

Weingartia neocumingii  Backeberg 1950
Syn. Rebutia neocumingii (Backeberg) D.R. Hunt 1987
Named for: Hugh Cuming (1791-1865) English naturalist, + prefix Greek néos = new 
The globose to short cylindrical stem has 16 - 18 ribs of tubercles, typically spiraling around the body. Tubercles bear 2 - 8 central and 5- 24 brownish radial spines. In early Summer, bright yellow to orange flowers are produced all over the body with up to 4 flowers per areole.
 
Native to dry valleys of the Andes of Bolivia and Peru growing at up to 9800 ft above sea level. Needs a cold, dry Winter to flower well. A very variable species with many synonyms and several forms.

Below: Some very old plants in the former Holly Gate Cactus Nursery reference collection.

Weingartia neocumingii var neocumingii  Backeberg 1950
Syn. Rebutia neocumingii (Backeberg) D.R. Hunt 1987