DICOTYLEDONOUS PLANTS 51 



or oblong, thin-shelled. Kiver bottoms. Rarely native east of the 

 Mississippi River, but widely planted for its fruit.* 



2. C. alba, Nutt. Shellbark Hickory. A large tree with bark 

 scaling off in long plates, young twigs and leaves downy, becoming 

 smooth with age. Leaflets 5, the lower ones oblong-lanceolate, the 

 upper one longer and ob ovate, taper-pointed at the apex, narrowed 

 to the sessile base. Inner bud-scales becoming large and conspicu- 

 ous. Staminate catkins in threes. Fruit globose, husk thick, split- 

 ting into four sections, nut white, compressed, ■4-angled, pointed, 

 thin-shelled. On rich soil. More common N. Wood strong and 

 elastic, but not durable when exposed.* 



3. C. sulcata, Nutt. Big Shellbark, King Nut, Bull Nut. A 

 tree 70-90 ft. high, with shaggy bark. Leaflets 7 or 9, the terminal 

 one nearly sessile. Fruit lai-ge, ovoid or nearly so, 4-grooved toward 

 the outer end, the husk very thick, nut pointed at each end, lJ-2 in. 

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

 Common in rich, damp soil W. 



4. C. amara, Nutt. Pignut, Swamp Hickory. A medium- 

 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.S;. Birch Family. 



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

 usually deciduous stipules. Flowers moncEcious in cylindri- 

 cal or subglobose catkins, staminate catkins drooping ; flowers 

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

 and 2-4-parted; stamens 2-10, distinct. Pistillate catkins 

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

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

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



I. CARPraus, L. 



Trees with thin, straight-veined leaves, which are folded 

 in the bud. Flowers appearing before the leaves ; staminate 

 flowers in slender drooping catkins, sessile at the end of the 

 growth of the previous season ; stamens 3-12, subtended by 

 a bract, filaments forked, anthers hairy. Pistillate catkins 



