DICOTYLEDONOUS PLANTS 53 



very thin, round-cordate, acute or slightly taper-pointed, irregularly 

 toothed, nearly smooth above, downy below. Involucre longer than 

 the nut and partially enclosing it, glandular-hairy. Nut subglobose, 

 pointed, edible. On rich soil, borders of meadows and fields, and 

 ill oak-open ings. 



2, C. rostrata, Ait. Beaked Hazelnut. A shrub 4-8 ft. high. 

 Young t^Aigs near ends smooth. Leaves thin, little, if at all, heart- 

 shaped, doubly serrate or incised, taper-pointed, stipules linear- 

 lanceolate. Involucre completely covering the nut and prolonged 

 into a beak beyond it. Common N. [The latter species is not 

 nearly as widely distributed as the former ; they cannot be readily 

 distinguished from each other until the fruit is somewhat mature. 

 The principal points of difference discernible before the fruit is 

 nearly mature are the hairy twigs of No. 1 and the smooth ones of 

 No. 2, and the fact that No. 1 has buds rounded at the af)ex and 

 more slender and longer staminate catkins, while No. 2 has buds 

 acute at the apex and thicker and shorter staminate catkins.] 



rv. BETULA, Toum. 



Trees with slender, aromatic twigs and thin, usually straight- 

 veined leaves. Staminate catkins drooping, flowers usually 3 

 in the axil of each bract, stamens 4, short, anthers 1-celled. 

 Pistillate catkins erect, flowers 2 or 3 in the axil of each bract ; 

 ovary sessile, 2-celled, styles 2 ; bracts 3-lobed ; perianth none. 

 Nut broadly winged.* 



1. B. nigra, L. Black Birch, River Birch. A medium-sized 

 tree with reddish-brown bark. Leaves rhombic-ovate, acute at the 

 apex, acute or obtuse at the base, sharply and doubly serrate, white- 

 downy below, becoming smoother with age, petioles short. Stami- 

 nate catkins 2-3 in. long. Pistillate catkins 1-1^ in, long, peduncles 

 short, bracts nearly equally 3-cleft, woolly. River banks, especially 

 S. and W.* 



2. B. lenta, L. Cherry Birch. Leaves ovate or oblong-ovate, 

 acute, heart-shaped, finely and doubly serrate, silky when young ; 

 petioles about ^ in. long. Staminate catkins clustered, 3-4 in. long. 

 Pistillate catkins sessile, about 1 in. long, cylindrical bracts spread- 

 ing, acute, smooth. River banks, especially N. A large tree with 

 aromatic twigs. The oil contained in the bark and twigs is distilled 

 and used as a substitute for wintergreen.* 



3. B. populifolia, Ait. Gray Birch. A tall shrub or slender, 

 straggling tree, 15-30 ft. high, seldom growing erect, often several 

 trunks springing from the ground almost in contact and slanting 

 away from each other. Leaves triangular, with a long taper point 



