484 



GVMNOSPERMS 



Sperms, in cycads, iji-37, UQ'' in Ginkgo, 

 206, 207; Coniferalcs, 316, 317-20; 

 Ctipressus, 3ig 



Spheuoptcris, 8, 16 



Sponsy tissue, 1 10, iig, 201, 30 j 



Spore mother-cell, 2S7 



Sporophyll, reduction, 101; evolution, 

 108; size, 113 



Spur, 186, 235, 2j6, 2j7, 25S; develop- 

 ment, 2g3 



Stalk cell, 128, 130, 308; Microcycas, 311 



Stangeria, 74; megaspore, /// 



Stem, morphology, 150 



Stephowspermiim, 18, 25 



Stomata, 263, 264, 265, 273 



Strobilus, 57, 99, loi, 102; Evolution of, 

 108; axillary, no; ovulate in Conife- 

 ralcs, 289, 2go-30i; young, 2pj 



Suspensor, of cycads, 145, 147; Conife- 

 ralcs, 351, 353 



Tapetum, 285 



Taxares, 230 



Taxodium mucronatiini, 222, 225 



Taxonomy, of cycads, 161; key, 163 



Taxus, 245, 246; strobili, 285, 300; gamc- 



tophyte, 319, 324, 331 

 Thuja plicaia, 225; T. occidentalis, 2jg, 



300, 346 



Torreya, ovule, 2g2; archegonium, 329; 



fertilization, 333 

 Triassic, 3, 4 

 Trichosanlhes, 84, 245 

 Trigonocarpon, 26 



Tsiiga, dwarfing, 225; growth-rings, 240 

 Tyloses, 245 



Venation, 191, ig4 



Ventral canal cell, 123; nucleus, 121, 122; 

 evolution of, 123; Coniferales, 327, 32Q 

 Vernation, 92, g4, pj 



Welwitschia, 384; stem, 386; leaf, 387, 388; 

 spicular cells, 38^; bundle, 3gi; stro- 

 bili, jpj, jpj, JP7; flower, 3g4, 3g8; 

 ovule, 3()q; pollen, 400; embryo, 402, 

 404; seedling, 405, 406 



Williamsonia, 43, 45, 59 



W illiamsoniella, 45 



Xerophyte, g7 



Xylem, Cycadofilicales, 13, 14; Bennetti- 



tales, 46-48; cycads, S2-go; Ginkgo, 



195 



Yucca, 55, 2ig 



Zamia, 66, 67; Z. pygmaea, 80; Z. flori- 

 dana, diagram of stem, g2; ovulate 

 cone, 107; megaspore, ///, 118 



r printed" 

 IN USA 



