578 



BOTANY OF THE LIVING PLANT 



Tetrad, a group of four spores re- 

 sulting from division of one spore- 

 mother-cell, 466 (Fig. 393), 467 

 (Fig. 394) ; its relation to ^len- 

 delian segregation, 475. 



Tetrad-division of a spore-mother- 

 cell, first into 2, then into 4, form- 

 ing the tetrad ; reduction of 

 chromosomes accompanies it, 249, 

 250 ; in formation of pollen, 249 

 (Fig. 194) ; in formation of em- 

 bryo-sac, 261 (Fig. 207), Chap. xxxi. 



Tetra-merous, with parts in whorls 

 of four, 231. 



Tetra-spores, of Red Seaweeds, 389 ; 

 of Dictyota, 3S7. 



Tetraphis, gemmae of, 359. 



Thalictrum, somatic parthenogenesis 

 in, 477. 



ThallopM^ta, plants with no clear 

 distinction of stem and leaf, 3, 371, 

 Chap, xxiii. ; alternation in, 481, 

 482. 



Timiriazeff's demonstration, 102 (Fig. 



75). 



Tissues, of stem, 33 ; of leaf, 61 ; 

 of root, 72 ; mutual tensions of, 

 142 (Fig. loi). 



Toad-flax, zygomorphy of, 240 (Fig. 

 189) ; deposit of seeds, 292. 



Toad-stools, 402, 403, 441. 



Tooth-wort, parasitism of, 193 (Fig. 

 144). 



Torus, of bordered pits, 306 (Fig. 

 240). 



Toxins, 460. 



Tracheae, a general term including 

 tracheides and vessels. They have 

 woody walls and no cell-contents 

 when mature, 38. 



Tracheid, a cell with complete woody 

 walls and no cell-contents : fibrous, 

 39 (Fig. 24), 50 (Fig. 37) ; of 

 Coniferous wood, 305 (Figs. 247- 

 248) ; of Fern, 332 (Figs. 270, 271). 



Transpiration, exhalation of water- 

 vapour, 85 ; transpiration stream, 

 87 ; conveys salts, 92. 



Transverse plane, in a floral-dia- 

 gram the plane perpendicular to the 

 median plane, 229. 



Trefoil (Lotus), 522 (Fig. 431). 



Trichocolea, structure of, 366. 



Trichodesmium, of " Red-Sea." 457. 



Trichogyne, the receptive filament 

 of Red Seaweeds, 388 (Fig. 327) ; 

 of Fungi, 411, 429 ; of Collema, 440. 



Tricoccae, 493, 515. 



Trimerous, with parts in whorls of 

 three, 231 (Fig. 178). 



Triticum repens, vegetative propa- 

 gation of, 218. 



Triticum vulgare, analysis of, 547 ; 

 origin of, 548. 



Tropaeolum, structure of lamina, 64 

 (Fig. 46) ; exudation of water from 

 leaf, 92 (Fig. 69). 



Tropophyte, a plant growing in the 

 tropics, 179. 



Truffle (Tuber), 429, 438 (Fig. 371). 



Tuber, mycorhizic of Orchids, 201 

 (Fig. 152). 



Tubercles, on Leguminous roots, 106 ; 

 fixation of nitrogen in, 106, 204. 



Tuberous stems, 165. 



Tubiflorae, 535. 



Tulip, chromoplasts in petals, 244 ; 

 flower of, 492, 494. 



Turgor (turgescence), the tense con- 

 dition of living cells owing to 

 pressure of the protoplast on the 

 wall, 24, 25 ; of stoma, 91 (Fig. 

 68) ; movements due to changes 

 of, 129 ; rigidity based on, 138, 

 141. 



Turnip (Brassica), analysis of, 541 ; 

 origin of, 542. 



Twining stem, 182. 



Ulothrix, 392 (Fig. 330) ; isogametes 



of, 461. 

 Ulotricales, 392. 

 Umbellales, 493, 524. 

 Umbelliferae, fruit of, 287 ; flower of, 



524- 



Unit-characters, pairs of, 475. 



Uredineae, 442 (Figs. 375-384) '> life- 

 history of, 449-481. 



Uredospores (or Summer-spores of 

 Puccinia), 442 (Figs. 375, 377) ; 

 germination of, 443 (Fig. 378). 



Ustilagineae (Smuts), 450. 



Ustilago, germination of, 450 (Fig. 



385). 

 Utricularia, urns of, 209. 



Vaccinium, 526. 



Vacuole, a cavity in the cytoplasm, 



• filled with cell sap, 22 (Figs. 12, 13), 



29. 

 Valerian, wind-borne fruit of, 290 



(Fig. 233). 



