Deciduous trees with close or shaggy bark, terete twigs and continuous pith. Buds large, sometimes stalked, often superposed. Leaf-scars alternate, shield-shaped or 3-lobed, large; bundle-traces numerous, mostly in 3 more or less definite groups. The fruit, present in winter, either on the tree, or mostly scattered on the ground, may be classed as a kind of dry drupe, or tryma. Hicoria Raf.
Fig. 43. Carya cordiformis.
Fig. 44. Carya ovata.
Bud-scales valvate, in pairs
b. Buds covered with yellow-brown hairs; kernel sweet
b. Buds sulfur-yellow, scurfy; kernel bitter
Bud-scales imbricate, usually more than 2 exposed
b. Terminal bud large, usually over 10 mm. long, mostly hairy; fruit with a thick husk
c. Outer bud-scales persistent, the bud shaggy in appearance
d. Twigs dark reddish-brown; fruit 3-6 cm. long
d. Twigs orange-brown or buff-colored; fruit 4-6. 5 cm. long
c. Outer bud-scales falling early, the bud neat in appearance
b. Terminal bud small, usually less than 10 mm. long; mostly glabrous or scaly; fruit with a thin husk
c. Terminal bud essentially glabrous (hairy if the outer bud-scales have fallen)
d. Fruit obovoid, the husk usually splitting only part way down (or tardily splitting)
d. Fruit usually ellipsoid or subglobose, the husk splitting promptly to the base
Terminal bud covered with silvery scales
1. C. illinoensis (Wang.) K. Koch.Pecan. (C. pecan (Marsh.) Engl, and Graebn.). Tree up to 50 m. high, and with a trunk diameter of 6-12 dm., buttressed at the base; bark very thick, furrowed, ridged; buds flattened, with paired valvate narrow scales covered with jointed hairs; fruit elongate, the ripe husk splitting to below the middle; nut reddish-brown, elongate, subcylindric, ellipsoid or ovoid; shell thin; kernel sweet. Bottomlands, Indiana to Iowa, south to Alabama and Texas.
2. C. cordiformis (Wang. )K. Koch. Bitternut Hickory. A slender tree 15-50 m. high, the trunk 3-7. 5 dm. in diameter;bark close and rough; bud-scales valvate in pairs, bright yellow; husk of fruit thin, splitting slowly into 4 valves; nut globular, thin-walled; seed extremely bitter. Woods, Florida to Texas, north to New Hampshire, Minnesota, and Nebraska (Fig. 43).
3. C. ovata (Mill.) K. Koch.Shagbark Hickory. A handsome tree 20-28 m. high, the trunk 3-6 dm. in diameter; bark shaggy, exfoliating in rough strips; twigs gray or brown, puberulent or glabrate; bud scales several, imbricated; fruit-husk thick, splitting quickly into four valves when mature; nut flattish-globular, thin-walled; seed sweet. Rich woods and slopes, Florida to Texas, north to Maine, Minnesota, and Nebraska (Fig. 44).
4. C. laciniosa (Michx.f.) Loud. Shellbark Hickory. A tree 20-40 m. high, the trunk 3-6 dm. in diameter; bark separating into long narrow straight plates; twigs buff or orange; fruit-husk thick, splitting quickly into four valves when mature; nut large, 3-5 cm. long, angular, thick-walled; seed sweet. Bottomlands, New York to Iowa and Nebraska, south to Alabama and Louisiana (Fig. 45).
5. C. tomentosa Nutt. Mockernut. White Hickory. (C. alba K. Koch). A tree 20-40 m. high, the trunk 3-7.5 dm. in diameter; bark close, rough, but not shaggy or exfoliating; twigs tomentose-pubescent; outer bud-scales falling early, giving the bud a clean neat silvery appearance; fruit-husk thick and hard, splitting to the base; nut globular, quite thick-shelled (hence the common name, mockernut); seed sweet. Woodlands, Florida to Texas, north to Vermont, Michigan, and Nebraska (Fig. 46).
6. C. glabra (Mill.) Sweet Pignut Hickory. A tree 20-30 m. high, the trunk 3-10 dm. in diameter; bark close, rough; twigs glabrous or nearly so; terminal bud small, less than 10 mm. long; fruit obovoid, the husk thin, splitting only part way to the base;nut rather thick-shelled; seed rather bitter. Dry woods, Vermont to Illinois, south to Florida and Louisiana (Fig. 47).
Fig. 45. Carya laciniosa.
Fig. 46. Carya tomentosa.
Fig. 47. Carya glabra.
Fig. 48. Carya ovalis.
7. C. ovalis (Wang.) Sarg. Oval Pignut Hickory. Red Hickory. A tree 20-40 m. in height, 3-10 dm. in diameter; bark closely and deeply furrowed; twigs red-brown, glabrous; terminal bud small, less than 10 mm. long; fruit oval in vertical section, the husk thin, splitting freely to the base; nut 4-ribbed above the center; kernel rather sweet. Rich soil, Massachusetts to Michigan and Iowa, south to Georgia and Arkansas (Fig. 48).
8. C. pallida (Ashe) Engl. and Graebn. Pale Hickory. Sand Hickory. A tree usually 10-15 m. high, with trunk diameter of 3-6 dm. ; bark very pale to dark gray, becoming deeply furrowed; buds silvery, the terminal about 6 mm. long; fruit yellow-scaly, 1. 5-4 cm. long, the husk thin, tardily splitting to base; nut thin-shelled; kernel sweet. Dry sandy soil, mostly on or near the coastal plain, Louisiana to Florida, north to Tennessee and New Jersey.