Dicotyledones. 33 



1. Quercus rubra, L. (L., ruber, red.) RED OAK. Leaves oval or obovate, 

 obes usually triangular and bristle-tipped. Acorns about i inch long, and about 

 2-4 times as long as the flat or saucer-shaped cup. In rich or poor soils. 



2. Quercus alba, L. (L., albus, white.) WHITE OAK. Leaves obovate, green 

 above and pale or somewhat glaucus beneath, divided into 3-9 oblong lobes, 

 which are often toothed at the apices, but not bristle-pointed. Acorns ovoid- 

 oblong, becoming sometimes i inch long and from 3 to 4 times as long as the 

 shallow cup. In various soils. 



3. Quercus macrocarpa, Michx. (Gr., makros, long; karpos, fruit.) BUR OAK. 

 Leaves obovate or oblong-obovate, variously lobed, pinnatifid or crenate, bright 

 green above and grayish tomentulose beneath. Acorn from \ to i\ inches long, 

 about half immersed in, or scarcely exceeding, the cup, whose uppermost bracts 

 are extended in the form of a fringe. In rich soil. 



4. Quercus Prinus, L. (Gr., prinos, the evergreen oak.) ROCK CHESTNUT 

 OAK. Leaves obovate, oblong, or oblong-lanceolate, and coarsely crenate, dark 

 green and smooth above, grayish tomentulose beneath. Acorns I to ij inches 

 long, and from 2 to 3 times as long as the tuberculate cup. In dry soil or on rocky 

 banks. 



URTICACE-ffi. NETTLE FAMILY. 



Trees, shrubs, or herbs with monoecious, dioecious, or sometimes 

 perfect flowers, and leaves with stipules. The perfect flowers with a 

 regular, inferior calyx. Ovary superior, i -celled, rarely 2-celled. Sta- 

 mens as many as the calyx lobes, and opposite them, or fewer. 



I. ULMUS. Elm. 



(The classical Latin name.) 



Trees with 2-ranked, simple, serrate, straight-veined leaves, with per- 

 fect or polygamous flowers in lateral clusters, expanding before the 

 leaves. Calyx 4-9-lobed and campanulate. Flowers in clusters on 

 twigs of the preceding season ; cells of the ovary 1-2, each with a 

 single ovule ; the 2 styles diverging, and stigmatic along the inner 

 edge ; fruit a i -seeded samara, winged all around. 



1. Ulmus Americana, L. AMERICAN or WHITE ELM. Leaves oval or obo- 

 vate, only slightly roughened above, 2-4 inches long. Branches without corky 

 wings (as in the case .of those of the winged elm, Ulmus alata). Samara ovate- 

 oval, nearly 5 inch long, ciliate on the margins of the reticulate-veined wing. Along 

 streams or in rich and moist soil. 



2. Ulmus fulva, Michx. (L.,/u/vus, tawny.) SLIPPERY or RED ELM. Leaves 

 from ovate to obovate, much roughened above, doubly serrate, 4 to 8 inches long. 

 Branches without corky wings, inner bark very mucilaginous. Samara from to 

 | of an inch long, without ciliate borders. In rich soil. 



