Tetrapetalous 



OF BOTANICAL TERMS, 



Thorn 



TETRAPET'AlOUS, having four 

 petals. 



TETRAPH'YLLOUS, four-leaved. 

 Often used for Tetrasepalous. 



TETRAQ'UETROUS, having four 

 salient angles. Compare Te- 

 tragonal. 



TE'TRARCH, a term applied to 

 a tibrovascular cylinder which 

 represents four tibrovascular 

 bundles. 



TETRASEP'ALOUS, of four se- 

 pals. See Tetr APHYLLOUS. 



TETRASPER'MOUS, four-seeded. 



TETRAsPORAN'GIUM, a sporan- 

 gium (unicellular) containing 

 tetraspores. 



TET'RASPORE, a gonidium or 

 asexually produced spore in 

 Florideae. So called from 

 being often produced four 

 together in a mother-cell ; 

 tetragonidium. 



TETRAs'TICHOUS, in four verti- 

 cal rows upon a stem. 



THAlAmiFLO'RAL, having the 

 stamens inserted upon the re- 

 ceptacle. Compare Corolli- 

 floral and Calycifloral. 



THAlAmIFLO'ROUS, see Thala- 



MIFLORAL. 



THALAMUS (pi. Thal'ami), the 

 receptacle of a flower. 



THAlAS'SOPHYTE, a sea-alga. 

 (Rare.) 



THAl/LOGEN,see Thallophyte. 



THAL'LOID, having the form or 

 nature of a thallus. Compare 

 Foliose and Frondose. 



THAlloT'DAL, see Thalloid. 



THAL'LOME, see Thallus. 

 Compare Caulome. 



THAL'lOPHYTE, a plant whose 

 vegetative body is a thallus, as 

 a lichen, fungus, or alga; cel- 

 lular cryptogam; thallogen. 

 Compare Cormophyte. 



THAl/LUS(pl. Thal'll), a vegeta- 



tive body without true leaf or 

 stem, as that of most crypto- 

 gams; thallome. 



THAL LtJS PLAC0'DE§ (obs.), see 

 Foliaceous Thallus. 



THAl'LUS THAMNO'DES (obs.), 

 see Fruticose Thallus. 



THE'CA (pi. The'cse), a sporan- 

 gium or anther-cell. (Rare.) 

 Formerly in general use for 

 ascus, and still used by some 

 writers for the sporangium or 

 capsule of mosses. » 



THE'CAPHORE (obs.), see Gyno- 

 phore. 



THE'CASPORE, see Ascospore. 



THEgiF'EROUS, bearing asci or 

 other thecas; thecigerous. 

 (Rare.) 



THECIF'EROUS, see Thecif- 

 erous. 



THERMOT'ROPISM, the property 

 or phenomenon of movement 

 under the influence of heat 

 or cold. Curvature towai'd a 

 source of heat is called positive 

 thermotropism; curvature in 

 the opposite direction, negative 

 thermotropism. 



THICK'ENING LAYER, an ap- 

 parent layer of cellulose de- 

 posited upon the inner surface 

 of a cell-wall. It appears as a 

 layer only because of its power 

 of absorbing water in a differ- 

 ent degree from the remainder 

 of the cell-wall. 



THICK'ENtNG RING, the cam- 

 bium-ring, or any other ring 

 or layer of thickening or meri- 

 stematic tissue. 



THORN, a degenerated, sharp- 

 pointed branch, either simple, 

 as in the thorn-apple, or 

 branched, as in the honey- 

 locust. Sometimes applied to 

 other large, sharp, rigid pro- 

 cesses. Compare Spine and 

 Prickle. 



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