Trees , to 44 m. Bark light gray or brownish, ridged with appressed scales or exfoliating with small platelike scales. Twigs tan to reddish brown, slender, hirsute, conspicuously scaly, sometimes becoming glabrous. Terminal buds yellowish brown, oblong, 6-12 mm, hirsute, scaly; bud scales valvate; axillary buds protected by bracteoles fused into hood. Leaves 4-7 dm; petiole 4-8 cm, glabrous to scurfy with short single hairs or scattered fascicles. Leaflets (7-)9-13(-17), lateral petiolules 0-7 mm, terminal petiolules 5-25 mm; blades ovate-lanceolate, often falcate, 2-16 × 1-7 cm, margins finely to coarsely serrate, without tufts of hairs, apex acuminate; surfaces abaxially hirsute or with scattered unicellular and 2-rayed fasciculate hairs, scaly with large peltate scales and small round peltate scales, adaxially without hairs or rarely hirsute with unicellular hairs along midrib, and with scattered 2-6-rayed fasciculate hairs, moderately scaly in spring. Staminate catkins essentially sessile, to 18 cm, stalks with small capitate-glandular trichomes; anthers sparsely pilose. Fruits dark brown, ovoid-ellipsoid, not compressed, 2.5-6 × 1.5-3 cm; husks rough, 3-4 mm thick, dehiscing to base or nearly so, sutures winged; nuts tan to brown and mottled with black patches, ovoid-ellipsoid, not compressed, not angled, smooth; shells thin. Seeds sweet. 2 n = 32. Flowering spring. Along stream banks, river flood plains, and on well-drained soils; 0-600(-1000) m; Ark., Ill., Ind., Iowa, Kans., Ky., La., Miss., Mo., Okla., Tenn., Tex.; Mexico. Carya illinoinensis is the state tree of Texas.
Native Americans used Carya illlinoinensis medicinally as a dermatological aid and as a remedy for tuberculosis (D. E. Moerman 1986).
From Flora of Indiana (1940) by Charles C. Deam
Infrequent or local in the Ohio River Bottoms as far east as Bethlehem, Clark County, up the Wabash River as far north as 4 miles south of Covington, Fountain County, up White River into Greene County, and known up the Muscatatuck River into Washington County. It was formerly a common tree in Point Township of Posey County and in the southwest part of Gibson County. Its habitat is river bottoms that are usually inundated annually.
Bark deeply furrowed; lfls 11-17, oblong- lanceolate, the lateral conspicuously falcate, the terminal commonly on a stalk 2-4 mm; frs in spikes of 3-10, ellipsoid or cylindric, 3-5 cm, narrowly winged to the base; nut ellipsoid or cylindric, terete, 2.5-4 cm, brown, smooth, short-pointed; kernel edible, each half barely notched at the tip; 2n=32. Wet alluvial forests; sw. O. to Io. and e. Kans., s. to Ala., Tex., and N. Mex. (C. pecan) C. آrownii Sarg. is a hybrid with C. cordiformis; C. خussbaumeri Sarg., with C. laciniosa; C. جecontei Little, with C. aquatica; and C. سchneckii Sarg., with C. tomentosa.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.