792" GLOSSARY. 



Truncate. Applied to leaves in which the summit appears as though the 



upper portion had been cut squarely off. as in the tulip poplar. 

 Tuber. An enlarged, swollen portion of an underground stem, as the 



white potato (p. 326). 

 Tubercles. The small nodules on the rootlets of the Leguminosae, and 



which are capable of assimilating atmospheric nitrogen. 

 Tunicated. A bulb composed of a number of concentric fleshy scales, 



as in the onion. 

 Turbinate. Shaped like an inverted cone ; top-shaped. 

 Turgescent. Applied to cells that are filled with cell sap and distended 



beyond their normal size. 

 Umbel. An inflorescence consisting of a number of flowers in which the 



pedicels are of equal length and arise from the summit of the same 



shoot, as in the Araliaceae and the milkweeds. The inflorescence of 



the Umbelliferae consists of compound umbels, in which the pedicel 



of each flower has a secondary umbel or umbellet (pp. 640-642). 

 Uncinate. Applied to an achene having a hooked summit. 

 Undulate. A leaf that has a repand or wavy margin, as in the witchhazel. 

 Unguiculate. A petal that is contracted at the base into a claw or stalk. 

 Uniseriate (Uniserial). Having the cells in a single row or series. 

 Unisexual. Applied to plants in which the staminate and pistillate flowers 



are developed on different individuals, as in the willow and poplar. 

 Utricle. An inferior achene-like fruit, having a thin and loose pericarp. 



as in Chenopodium (p. 420). Also applied to the perigynium. or 



inflated sac which encloses the ovary, of the flowers of Carex. 

 Valvate. Applied to flower buds when the rudimentary sepals or petals 



touch each other at their margins (p. 389). Also applied to the 



dehiscence of capsules when the separation is at the margins of the 



carpels. 

 Vernation (Prefoliation). The study of the folding of the leaves in buds. 

 Verrucose (Verrucous). A surface covered with wart-like elevations, 



as in some of the gourds. 

 Versatile. Applied to anthers which are attached, transversely or hori- 

 zontally, to the summit of the filament, as the T-shaped stamens of 



the tiger lily. 

 Verticillate. Applied to leaves or flowers which are arranged in whorls 



at the nodes. 

 Villous. Applied to a surface having long, soft hairs and which are not 



matted or interwoven, 

 Vittae. The oil tubes in the pericarp of the fruits of a large number of 



the Umbelliferae. 

 Woolly. Covered with long, curly and more or less matted hairs. Often 



used in the same sense as tomentose, lanate or pubescent. 

 Xylem. The tracheae and wood fibers of a fibrovascular bundle (pp. 312 



ard 341). 

 Zoospore. A motile asexual spore (p. 5). 

 Zygoraorphic (Zygomorphous). Applied to flowers which can be bisected 



into similar halves in only one plane. They are also spoken of as 



dorsiventral flowers (p. 393). 

 Zygospore (Zygote). A spore resulting from the union of two similar 



gametes or protoplasmic masses (pp. 5 and 19). 



