KEY TO THE FAMILIES. 



VI 1 



Fruit 2-celIed, a double sa- 

 mara. 

 Fruit 1-celled, a single samara. 

 Leaves alternate. 



Flowers not in aments. 

 Flowers or some of them in aments. 

 Staminate flowers in aments; 

 pistillate flowers 1-3 in a 

 cluster. 

 Staminate and pistillate flowers 

 both in aments. 

 Ovary 1-celled, many-ovuled; 



calyx not present. 

 Ovary 1-2-celled, each cell 

 1-ovuled. 

 Pistillate flowers 2-3 un- 

 der each scale of the 

 ament; fruit not waxy; 

 calyx present. 

 Pistillate flowers 1 under 

 each scale of the ament; 

 fruit waxy; calyx not 

 present. 

 Herbs (sometimes woody at base). 

 Leaves opposite. 



Flowers monoecious. 



Ovary 1-celled; stamens 2-5. 

 Ovary more than 1-celled; stamen 1. 

 Ovary 4-celled. 

 Ovary 3-celled. 

 Flowers perfect. 

 Leaves fleshy. 

 Leaves not fleshy. 

 Style 1. 



Calyx petal-like. 

 Calyx not petal-like. 

 Styles 2-5. 



Disk conspicuous; ovules on 



2 parietal placentae. 

 Disk not conspicuous, if 

 present; ovules on a basal 

 or central placenta. 

 Leaves not opposite. 

 Leaves whorled. 



Calyx present, closely investing the 



ovary. 

 Calyx none. 

 Leaves not whorled. 

 Flowers monoecious. 



Ovary 3-celled, 3-ovuled. 

 Ovary 1-celled, l-ovuled. 



Flowers with scarious bracts. 

 Flowers bractless, or, if 

 bracted, the bracts not 

 scarious. 

 Flowers perfect or dioecious. 

 Pistils more than one. 



aceraceae, 235. 

 Oleaceae, 287. 



Rhamnus, 236. 



Fagaceae, 121. 



Salicaceae, 112. 



Betulaceae, 119. 



Myricaceae, 118. 



Urticaceae, 122. 



Callitrichaceae, 231. 

 Euphorbiaceae, 230. 



Glaiix, 285. 



Nyctaginaceae, 135. 

 Isnardia, 247. 



Chrysosplenium, 193. 



Caryoph\i,laceae, 141. 



Haloragidaceae, 253. 

 Ceratophyllaceae, 151. 



Euphorbiaceae, 230. 

 Amaranthaceae, 134. 



Chenopodiaceae, 132. 



