3. =Cárya tomentòsa=, Nutt. (MOCKERNUT. WHITE-HEART HICKORY.) Leaflets 7 to 9 (mostly 7), lance-obovate, pointed, obscurely serrate or almost entire, the lower surface as well as the twigs and the catkins tomentose when young. Fruit globular or ovoid, usually with a very hard, thick husk slightly united at base. Nut somewhat hexagonal, with a very thick shell and well-flavored kernel. A tall, slender tree, 60 to 100 ft. high, with a rough deeply furrowed, but not shaggy bark. Common on dry hillsides throughout. [Illustration: C. microcárpa.] 4. =Cárya microcárpa=, Nutt. (SMALL MOCKERNUT.) Leaflets about 5 (5 to 7), oblong-lanceolate, long-pointed, finely serrate, smooth, glandular beneath; buds small, ovate. Fruit small, subglobose, with a thin husk; nut not sharply angled, with a thin shell; edible. A large tree, 70 to 90 ft. high; New York, Pennsylvania, and westward. [Illustration: C. porcìna.] 5. =Cárya porcìna=, Nutt. (PIGNUT. BROOM-HICKORY.) Leaflets 5 to 7 (usually 7), oblong-ovate, acuminate, serrate, smooth. Fruit pear-shaped to oval, somewhat rough, splitting regularly only about half-way. Nut large (1½ to 2 in. long), brownish, somewhat obcordate, with a thick, hard shell, and poor, bitter kernel. Tall tree, 70 to 80 ft. high, with dark-colored heart-wood, and rather smooth bark. Common on ridges. [Illustration: C. amàra.] 6. =Cárya amàra=, Nutt. (BITTERNUT. SWAMP-HICKORY.) Leaflets 7 to 11, lanceolate to oblong-lanceolate, serrate with deep teeth. Fruit roundish-ovate, regularly separable only half-way, but friable at maturity. Nut small, white, subglobose, with a very thin shell and an extremely bitter kernel. Large tree with orange-yellow winter buds, and firm, not scaly, bark. Wild throughout, and sometimes cultivated. [Illustration: C. olivæfórmis.] 7. =Cárya olivæfórmis=, Nutt. (PECAN-NUT.) Leaflets 13 to 15, ovate-lanceolate, serrate; lateral ones nearly sessile and decidedly curved. Fruit oblong, widest above the middle, with 4 distinct valves. Nut oblong, 1¼ in., nearer smooth than the other edible Hickory-nuts, the shell thin, but rather too hard to be broken by the fingers. The kernel is full, sweet, and good. A tall tree, 80 to 90 ft. high. Indiana and south; also cultivated, but not very successfully, as far north as New York City. ORDER =XXXIX. CUPULÌFERÆ.= (OAK FAMILY.) This order contains more species of trees and shrubs in temperate regions than any other, except the Coniferæ. The genus Quercus (Oak) alone contains about 20 species of trees in the region covered by this work. GENUS =83. BÉTULA.= Trees or shrubs with simple, alternate, mostly straight-veined, thin, usually serrate leaves. Flowers in catkins, opening in early spring, in most cases before the leaves. Fruit a leafy-scaled catkin or cone, hanging on till autumn. Twigs usually slender, the bark peeling off in thin, tough layers, and having peculiar horizontal marks. Many species have aromatic leaves and twigs.