12 ANALYTICAL KEY 



Plant not rush-like LiliacbAe, 279 



Divisions of the perianth unlike, 3 green sepals and 



3 colored petals. 

 Stem-leaves ovate or oblong, 3 in a whorl Trillium, 293 



Stem-leaves linear or nearly so ; flowers umbeled 



COMMELINACEAE, 264 



U. Stamens dissimilar, or only 3 with fertile anthers. 



Perianth of 3 herbaceous sepals and 3 colored ephemeral 



petals COMMELINACBAE, 264 



Perianth tubular, 6-lobed Pontederiaceae, 266 



M. Perianth present, adnate to the ovary V. 

 V. Stamens 1-2 ; flowers irregular. 



Anthers 2-celled ; seeds many Obchldaceae, 304 



Anthers 1-oelled ; seeds solitary Maeantaceae, 304 



V. Stamens 3 or more ; flowers mostly regular or nearly so W. 

 W. Climbing plant with net-veined ovate leaves Dioscoreaceae, 297 



W. Not climbing; leaves parallel-veined. 



Perianth woolly, only partially adnate to the ovary 



Haemodoraceae, 296 

 Perianth not woolly, adnate to the whole surface of the 

 ovary. 

 Aquatics ; flowers dioecious or polygamous Htdrocharitaceae, 85 

 Terrestrial ; flowers perfect. 

 Stamens 6 Amabtllidaceae, 297 



Stamens 3. 

 Leaves 2-ranked, equitaut; stamens opposite the 



outer segments of the perianth Ibidaceae, 299 



Leaves not 2-ranked, the cauline scale-like; stamens 

 opposite the inner segments of the perianth 



BUEMANNIACEAE, 304 



Class 2. DICOTYLEDONEAE 



Stems formed of bark, wood, and pith; the wood forming a zone between 

 the other two, and increasing, v\'heii the stem continues from year to year, 

 by the annual addition of a new layer to the outside, next the bark. Leaves 

 net-veined. Embryo with a pair of opposite cotyledons. Parts of the 

 flower mostly in fours or fives X. 



X. Corolla none ; calyx present or absent Y. 



Y. Flowers monoecious or dioecious, one or both sorts in catkins Z. 

 Z. Only one sort of flowers in catkins or catkin-like heads. 



Fertile flowers in a short catkin or catkin-like head Ubticaoeak, 344 



Fertile flowers single or clustered; the sterile in slender 

 catkins (except in Fagus). 

 Leaves pinnate ; fertile flowers and fruit naked Juglandaceae, 330 

 Leaves simple ; fertile flowers 1-3 in a cup or involucre Fagaceae, 337 

 Z. Both sterile and fertile flowers in catkins or catkin-like 

 heads a. 

 a. Ovary many-ovuled ; fruit many-seeded. . 



Ovary and pod 2-celled ; seeds not tufted Llquidambar, 453 



Ovary and pod 1-celled; seeds hairy-tufted Salicaceae. .320 



