Trichocyst: an organelle in the cell which throws off a fibril; a stinging thread. 

 Trichogyne: narrow extended part of female sex organ ( carpogonium ) in the 



Rhodophyceae. 

 Trichome: a hair; a thread of cells without the investing sheath in Myxophyceae. 

 True branching: branched by lateral division of a cell in a main filament. 

 Truncate: flat at the top; flatly rounded. 

 Tubercle (Tuberculate) : small raised thickenings on the wall, or at the base 



of spines. 

 Tychoplankton: floating or free-living organisms in shallow water of a lake 



intermingled with miscellaneous vegetation, usually near shore. 

 Travertine : a deposit of chalk-like calcareous material. 

 Umbonate: with a cone-shaped protrusion. 

 Undulate: wavy. 

 Uncinate: with a hooked apex. 

 Unilateral: on one side; arising from one side only. 

 Unilocular sporangium: a sohtary, one-celled spore-producing organ. 

 Uniseriate : arranged in a single row or series. 

 Uninucleate: with one nucleus. 

 Utricle: a small sac; a tubular bag or vesicle. 

 Vacuole: a space in the cytoplasm filled with cell sap, sometimes containing 



granules. 

 Valves: the two parts of the wall of diatoms, one of which is larger and fits 



over the smaller as a Hd; the two parts of a dinoflagellate cell. 

 Valve view: view from the top or bottom of a diatom cell so that the broader 



surface of the valve is seen. 

 Ventricose: bvJged or swollen on one side. 

 Vermiform: worm-like. 



Verrucae: short, stout projections, smooth or armed with teeth. 

 Verrucose: warty. 

 Vertical canals: canals which connect both outer and inner fissures of the 



raphe (q.v. ) in one part of the diatom cell with the fissures in the other 



part. 

 Vesicle: minute sac or cavity. 

 Volvocine tendency: evolutionary trend in green algae from a single motile 



cell toward simple colonies, and to colonies containing differentiated or 



specialized cells. 

 Water bloom: a conspicuous and abundant growth of planktonic algae, some- 

 times appearing suddenly, often forming a surface scum. 

 Xanthophyll: yellow pigment associated vdth chlorophyll. 

 Zonate: with bands; with concentric layers. 

 Zoospore: a motile, animal-like spore without a cell wall. 

 Zygospore: a thick- walled resting spore resulting from the union of gametes. 

 Zygote: a fertiHzed egg; a cell resulting from the union of gametes. 



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