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Wall - See: Cell wall, Exine, Pericarp
Wall pressure - inward force exerted by a cell wall on the cell contents by virtue of the elastic properties of the cell wall and by pressure from surrounding cells.
See also: turgor pressure
Wardian Case - a glazed terrarium created by Dr Nathaniel Bagshaw Ward (1791-1868) in about1829 for transporting plants and growing delicate mosses and ferns.
Wax - a diverse group of naturally-occurring greasy, hard, or soft and moldable high molecular weight solid substances of animal, plant or mineral origin. Wax may contain saturated hydrocarbons, esters of higher fatty acids, and higher alcohols. Most natural waxes contain a wide range of molecular sizes and therefore soften over a wide temperature range instead of melting at a specific temperature, as do substances of a uniform molecular size.
Weed - a plant growing in the wrong place.
Whorled - of leaves or other parts, not alternate or opposite but placed in a circle around the stem.
i. to droop, usually due to loss of turgor pressure.
ii. any of several diseases that cause plants to wilt and die.
Window - a translucent portion of the leaves of some succulent plants which allows light to penetrate to the photosynthetic layers.
i. a hard fibrous substance composed of cellulose bonded together with lignin formed as the main fluid conducting tissue or xylem making up the greater part beneath the bark of the trunk, branches and roots of trees, shrubs and other woody plants.
ii. a dense growth of trees, somewhat smaller in extent than a forest.
Wood gum - xylan
Wood sugar - xylose
Woody - made of or resembling wood. Of plant tissues hardened by accumulation of lignin.
Woolly - thickly covered with long hairs.
Wort - archaic Middle English word for any plant or herb, often one considered medicinal or otherwise useful in combination with a word describing the use e.g. lousewort, lungwort, glasswort
Old English: wyrt = herb, root.
Wrinkled - creased or folded up irregularly in every direction.