12 ANALYTICAL KEY 



Plant not rush-like Ltliackar, 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 COMMELINACEAE, 264 



Perianth tubular, 6-lobed Pontederiaceae, 266 



M. Perianth present, adnate to the ovai'y V- 

 V. Stamens 1-2; flowers irregular. 



Anthers 2-celled ; seeds many Orchidaceae, 304 



Anthers 1-celled ; seeds solitary Marantaceae, 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 Hydrocharitaceae, 85 

 Terrestrial ; flowers perfect. 

 Stamens 6 Amaryllidaceae, 297 



Stamens 3. 

 Leaves 2-ranked, equitant; stamens opposite the 



outer segments of the perianth Iridaceae, 299 



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

 opposite the inner segments of the perianth 



Burmanniaceae, 304 



Class 2. DICOTYLEDONEAE 



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

 the other two, and increa.sing, when 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 Urticaceae, 344 



Fertile flowers single or clustered; the sterile in slender 

 catkins (except in Fagus). 

 Leaves pinnate; fertile flowers and fruit naked Juolandaceae, 330 



Leaves si!iiple ; fertile flowers 1-3 in a cup or involucre Faqaceae, 337 

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

 heads a. 

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



Ovary and pod 2-celled ; seeds not tufted Liquida)nhar, 453 



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



