Dicotyledones. 23 



I. Quercus ribra, L. (L., ruier, 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. 



li. Quercus ilba, L. (L., a/faj, while.) 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., mains, long ; iarpos.fniit) 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 \\ inches 

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

 banks. 



URTICACE.S;. 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, l-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 Dreceding 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 i inch long, ciliate on the margins of the reticulate-veined wing. Along 

 streams or in rich and moist soil. 



2. Ulmus fiilva, Michx. (L.,^/i'a.r, tawny.) SLiPPERYor 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 

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



