1. =Carpìnus Caroliniàna=, Walt. (AMERICAN HORNBEAM. BLUE OR WATER BEECH.) Leaves ovate-oblong, pointed, sharply doubly serrate, soon nearly smooth. Fruit with the scales obliquely halberd-shaped and cut-toothed, ¾ in. long, nuts 1/8 in. long. A tree or tall shrub, 10 to 25 ft. high, with a peculiarly ridged trunk; the close, smooth gray bark and the leaves are much like those of the Beech. The wood is very hard and whitish. Common along streams; sometimes cultivated. [Illustration: C. Bétulus.] 2. =Carpìnus Bétulus=, L. (EUROPEAN HORNBEAM.) This cultivated species is quite similar to the American, but can be distinguished by the scales of the fruit, which are wholly halberd-shaped, having the basal lobes nearly equal in size, as shown in the cut; while the American species has scales only half halberd-shaped. GENUS =88. QUÉRCUS.= Large trees to shrubs, with simple, alternate, deciduous or evergreen, entire to deeply lobed leaves. The leaves are rather thick and woody, and remain on the tree either all winter or at least until nearly all other deciduous leaves have fallen. Flowers insignificant; the staminate ones in catkins; blooming in spring. Fruit an acorn, which in the White, Chestnut, and Live Oaks matures the same year the blossoms appear; while in the Red, Black, and Willow Oaks the acorns mature the second year. They remain on the tree until late in autumn. The Oaks, because of their large tap-roots, can be transplanted only when small. Most of the species are in cultivation. The species are very closely related, and a number of them quite readily hybridize; this is especially true of those of a particular group, as the White Oaks, Black Oaks, etc. There is no attempt in the Key to characterize the hybrids, of which some are quite extensively distributed. _Quercus heterophylla_, Michx. (Bartram's Oak), supposed to be a hybrid between _Quercus Phellos_ and _Quercus rubra_, is found quite frequently from Staten Island southward to North Carolina. * Cultivated Oaks from the Old World; bark rough; leaves more or less sinuated or lobed. (=A.=) =A.= Acorn cup not bristly 20. =A.= Acorn cup more or less bristly 21. * Wild species, occasionally cultivated. (=B.=) =B.= Leaves entire or almost entire, or merely 3- (rarely 5-) lobed at the enlarged summit. (=C.=) =C.= Ends about equal, petioles very short. (=D.=) =D.= Leaves small (2 to 4 in. long), evergreen, bark smooth, black (Live-oaks) 10. =D.= Leaves not evergreen in the North, somewhat awned when young, bark very smooth, black and never cracked (Willow-oaks). (=E.=) =E.= Down on the under side quite persistent 18. =E.= Under side soon smooth 19.