This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Trees with spreading branches, superposed buds, fragrant bark, and odd-pinnate leaves, with nearly or quite sessile leaflets, the terminal one sometimes early perishing. Staminate flowers in drooping cylindric aments, borne on the twigs of the previous year; perianth 2-6-lobed; stamens 8-40 in 2 or more series. Pistillate flowers solitary or several together on a terminal peduncle at the end of shoots of the season, the calyx 4-lobed, with 4 small petals adnate to the ovary at the sinuses; styles fimbriate, very short. Drupe large, globose or ovoid, the exocarp somewhat fleshy, fibrous, indehiscent, the endocarp bony, rugose or sculptured, 2-4-celled at the base, indehiscent, or in decay separating into 2 valves. [Name a contraction of the Latin Jovis glans, the nut of Jupiter.]
About 8 species, natives of the north temperate zone, one in the West Indies, 1 or 2 in the Andes of South America. Besides the following 3 others occur in the southwestern United States. Type species: Juglans regia L.
Fruit globose, obtuse, not viscid; petioles puberulent.
Fruit oblong, pointed, viscid; petioles pubescent.
Juglans nigra L. Sp. PI. 997- 1753-
A large forest tree with rough brown bark, maximum height about 1500, trunk diameter 8°, the twigs of the season and petioles puberulent, the older twigs glabrous or very nearly so. Leaflets 13-23, ovate-lanceolate, more or less inequilateral, acuminate at the apex, rounded or subcordate at the base, serrate with low teeth, glabrous or very nearly so above, pubescent beneath, 3-5' long, 1-2' wide; staminate aments solitary in the axils of leaf-scars of the preceding season, 3-5' long; drupes usually solitary or 2 together, globose or a little longer than thick, 1 1/2'-3' in diameter, glabrous but papillose, not viscid; nut corrugated, slightly compressed, 4-celled at the base and apex.
Juglans cinerea L. Sp. PI. Ed. 2, 1415. 1763.
A forest tree, resembling the Black Walnut, but smaller, rarely over 100° high and 30 in trunk diameter, the bark gray, smoother, the twigs, petioles and leaflets viscid-pubescent, at least when young. Leaflets 11-19, oblong-lanceolate, acuminate at the apex, scarcely inequilateral, obtuse, rounded or truncate at the base, serrate with low teeth; drupes racemed, oblong, densely viscid-pubescent, 2'-3' long and about one-half as thick, pointed; nut 4-ribbed, deeply sculptured, and with sharp longitudinal ridges, firmly adherent to the husk, 2-celled at the base.
In rich or rocky woods. New Brunswick and Ontario to North Dakota, south to Delaware, in the Alleghanies to Georgia, and to Mississippi, Arkansas and Kansas. Ascends to 2500 ft. in Virginia. Wood soft, rather weak, light brown; weight per cubic foot 25 lbs. April-May. Fruit ripe Oct.-Nov.