54 Kt;Y AND FLORA 



long, thick-shelled, with a very sweet kernel. Wood hard and heavy. 

 Common in rich, damp soil W. 



4. C. alba K. Koch. Mockek Nut, White-Heaut Hickory. A 

 large tree 70-100 ft. high, with close, rough bark ; catkins, twigs, 

 and under surfaces of the leaves downy and resinous-scented when 

 young. Leaflets 7-9, oblong-lanceolate or obovate-lanceolate, taper- 

 pointed. Fruit globose or nearly so, with a very thick, hard husk; nut 

 with 4 ridges toward the apex, very thick-shelled, with a small, sweet 

 kernel. On rich hillsides. Wood nmch like that of C. oi-ata. 



5. C. cordiformis K. Koch. Pignut, Swamp Hickory. A me- 

 dium-sized tree, with rather smooth bark. Leaflets 7-11, lanceolate 

 or oblong-lanceolate. Fruit not large, husk thin ; nut globular, with 

 a short point, very thin-shelled ; kernel extremely bitter. Moist soil, 

 common in the Middle States. 



17. BETULACE.^. Birch Family 



Trees or shrubs with alternate, simple, petioled leaves, with 

 usually deciduous stipules. Flowers moncecious iu cylindrical 

 or subglobose catkins. Staminate catkins drooping ; flowers 

 1-3 in the axil of each bract; calyx none or membranous 

 and 2^-parted; stamens 2-10, distinct. Pistillate catkins 

 drooping, spreading, or erect and spike-like ; flowers with or 

 without a calyx ; ovary solitary, 1-2-celled ; ovules 1-2 in each 

 cell. Fruit a 1-celled nut or a key.* 



I. CORYLUS L. 



Shrubs with prominently veined, cut-toothed leaves, which 

 are folded lengthwise in the bud. Flowers expanding before 

 the leaves. Staminate flowers in slender, drooping catkins ; 

 stamens 8, anthers 1-celled. Fertile flowers several in a 

 cluster or in very short catkins at the ends of the twigs of 

 the season ; ovary incompletely 2-celled; style short; stigmas 

 2 ; bractlets 2, becoming enlarged and inclosing the single 

 bony nut at maturity.* 



1. C. americana Walt. Hazelnut. A shrub 2-5 ft. high; young 

 twigs and petioles covered with brownish, stiff hairs. Leaves not 

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

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



