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a class of orange oxygenated carotenoid pigments in which one or more double bonds of a carotene have been substituted with hydroxy, methoxy, carboxy, epoxy and oxo (ketone) groups. Like carotene, xanthophylls assist photosynthesis.
Xenogamy - (Greek: xenos = stranger + gamos = marriage) cross pollination.
Xenograft - a graft from a different species
Xeranthemoides - with a dry appearance.
Xeromorphic - structural features of plants, xerophytes, adapted to dry conditions with a thickened cuticle or hairs protecting against moisture loss or with the appearance of such plants.
Xeriscape - an arid landscape or water-conserving garden in which xerophytic plants grow. A desert garden.
Xerophyte - a plant adapted to dry conditions.
Xylan - a yellow water-soluble gummy polysaccharide component of the hemicellulose of woody tissues, made from (1-4) linked xylose monomers. Derivatives may have arabinose (arabinoxylan) or 4-O-methylglucuronic acid (glucuronoxylan) side chains.
Xylose - (Greek: Xylon = wood) a white crystalline pentose (five-carbon) sugar isomeric with ribose, produced by hydrolysis or fermentation of xylans in straw or wood and an important dietary constituent of herbivores. Used in foods for diabetics as it can not be metabolised by humans. Non-fermentable by normal yeast.
Xylem - the main upward water-conducting tissue in vascular plants characterised by tracheary elements. Xylem may also be a supporting tissue, especially secondary xylem (wood).