KEY. 251 



Sterile aments drooping from the sides of the small twigs 

 near the end. Flowers preceding the leaves. Trunk ridged. 



Carpinus Americana^ Mx. 

 ( Water-Beech.) 

 Invplucral scales of the fertile aments lance-oblong, 

 bag-like, 1-flowered, forming a sort of strobile, resembling 

 that of the hop. Sterile aments 1-2 inches long, with the 

 jentire scales ciliate. Flowers appearing with the leaves. 

 Trunk even. * Ostrya Virginica, Willd. 



{Hop Hornbeam. Iron-wood.) 



793. Fertile flowers single under each scale of the 

 globular, bur-like aments ; ovary surrounded by 5 or 6, long, 

 linear-awl-shaped scales, persistent around the nut. Scales 

 of the sterile, cylindric aments kidney-shaped ; stamens 

 3-6. Leaves linear-lanceolate, pinnatifid with rounded 

 lobes, preceded by the flowers. 



Comptonia asplenifolia, Ait. 



Fertile flowers 2 or 3 under each scale. Nutlets 

 naked,^ winged, or woody 794 



794. Calyx of the fertile flowers of 4 little scales, ad- 

 lierent to the scales of the ovoid or oblong ament ; each 2- 

 flowered. Sterile aments elongated and drooping, with 5 

 bractlets, and 1-3 flowers under each scale ; each flower usu- 

 ally with a 4-parted calyx and 4 stamens. Aments (sterile 

 and fertile ones) often racemed. Alnus. 



{Alder.) 

 Calyx of the fertile flowers none. Three of the 

 fertile flowers under each 3-lobed bract, each consisting of a 

 naked ovary with 2 filiform stigmas. Fruit a broadly 

 winged nutlet. Sterile aments long and drooping, terminal 

 and lateral ; flowers golden-yellow, 3 of them and 2 bractlets 

 under each scale. Betula. 



{Birch) 



795. Flowers naked. Stamens numerous 796 



Flowers with a perianth — that is, a 4-lobed calyx. 

 Stamens 4. Both sorts of flowers in spikes. Calyx of the 

 fertile flowers becoming succulent in fruit ; and the whole 

 fertile spike transformed into a juicy (almost blackberry-like) 

 aggregate fruit. Ovary 2-celled and becoming, by the disap- 



