2. Juglans nigra Linnaeus, Sp. Pl. 2: 997. 1753.
Black walnut, noyer noir
Wallia nigra (Linnaeus) Alefeld
Trees , to 40(-50) m. Bark medium to dark gray or brownish, deeply split into narrow rough ridges. Twigs with distal edge of leaf scar notched, usually deeply, not bordered by well-defined band of pubescence; pith light brown. Terminal buds ovoid or subglobose, weakly flattened, 8-10 mm. Leaves 20-60 cm; petiole 6.5-14 cm. Leaflets (9-)15-19(-23), lanceolate or ovate-lanceolate, symmetric or weakly falcate, (3-)6-15 × 1.5-5.5 cm, margins serrate, apex acuminate; surfaces abaxially with capitate-glandular hairs, simple or 2-rayed fasciculate hairs, and scales scattered over veins and blade, axils of proximal veins with prominent tufts of fasciculate hairs, adaxially glabrous except for scattered capitate-glandular and fasciculate hairs on midrib; terminal leaflet small or often absent. Staminate catkins 5-10 cm; stamens 17-50 per flower; pollen sacs 0.8-0.9 mm. Fruits 1-2, subglobose to globose, rarely ellipsoid, 3.5-8 cm, warty, with scales and capitate-glandular hairs; nuts subglobose to globose, rarely ellipsoid, 3-4 cm, very deeply longitudinally grooved, surface between grooves coarsely warty. 2 n = 32.
Flowering spring (Apr-May). Rich woods; 0-1000 m; Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.
Variation of Juglans nigra in central Texas and south-central Oklahoma should be studied; specimens seemingly intermediate between J . nigra and both J . major and J . microcarpa have been seen from this area. E. C. Twisselman (1967) incorrectly reported that J . nigra was locally naturalized in California; his specimens were all J . hindsii (possibly introgressed with J . nigra ) and J . californica .
Juglans nigra is frequently cultivated as an ornamental, and the nuts are prized for their strong, distinctive flavor.
Native Americans used Juglans nigra medicinally as a miscellaneous disease remedy, a dermatological aid, and a psychological aid (D. E. Moerman 1986).