KEY TO THE FAMILIES 



Corolla, and sometimes calyx, lacking-. 



Flowers (at least the staminate ones) in catkins or 



catkin-like spikes; shrubs or trees. 

 Calyx (and corolla) lacking; i. e., the flowers are 



"naked." 



Dioecious; a single flower to each scale of the 

 catkin; fruit a 1-celled pod with many 



dow r ny-tufted seeds Salicacere 9 



Monoecious; staminate catkins drooping, pis- 

 tillate ones erect, with 2-3 flowers to 

 each scale of the cone-like inflorescence; 



seeds not downy Betulaccw 12 



Calyx present. 



Monoecious; staminate flowers in catkins; 

 pistillate ones 1-3 in a cup or in- 

 volucre Fagacea? 13 



Monoecious or dioecious; flowers in droop- 

 ing catkin-like spikes, the pistillate 

 ones becoming juicy multiple fruits.... 



No. 2 in Urtioaceie 13 



Flowers neither in catkins nor in catkin-like spikes. 

 Shrubs or trees. 



Leaves opposite. 



Fruit a samara; flowers inconspicuous. 



Leaves simple; stamens 3-8; fruit in 



pairs . Aceraceae 55 



Leaves pinnately-compound. 



Leaflets 3-5; stamens 4-5; samaras 



in pairs Aceracece 55 



Leaflets 5-9; stamens 2; samaras 



single Oleacese. . 71 



Fruit a tailed achene; flowers showy. . . . 



Clematis in Ranuiiculacew 26 



Leaves alternate. 



Leaves toothed; fruit a, samara or 



drupe Urticacere 13 



Leaves entire, revolute; fruit an achene, 

 tipped by the long, feathery 



style Cerocarpus in Rosacese 42 



Herbs; sepals when present often petal-like. 



Pistils several. .. . Thalictrum in Rammculaceee 24 

 Pistil 1. 



Ovary 2-celled Lepidium in Cruclfera? 30 



Ovary 1-celled. 



Leaves alternate. 



Styles 1-3; fruit a flat achene. . . 



Clienopodiaceee 17 



Style 1; fruit berry-like in 



shape Santalaeea? 15 



