This section is from the book "Woody Plants In Winter", by Earl L. Core, Nelle P. Ammons. Also available from Amazon: Woody Plants in Winter.
Trees with spreading branches, superposed buds, fragrant bark and brown chambered pith. Leaf-scars alternate, shield-shaped or 3-lobed, large; bundle-traces in 3 compound groups; stipule-scars none. The fruit, present in winter, may be classed as a tryma (see p. 11).

Fig. 41. Juglans cinerea.

Fig. 42. Juglans nigra.
a. | Terminal bud oblong, elongated; leaf-scar with a downy line across the top; pith dark brown. | 1. | J. cinerea |
a. | Terminal bud ovoid or subglobose; leaf-scar notched at top, without a downy line; pith light brown. | 2. | J. nigra |
1. J. cinerea L. Butternut. White Walnut. A tree 16-30 m.high, 6-9 dm. in diameter, with an open crown of spreading branches; bark gray, on old trunks divided by fissures into lighter flat-topped ridges; leaf-scars not notched; pith dark brown. Rich woods, New Brunswick to North Dakota, south to Georgia and Arkansas (Fig. 41).
2. J. nigra L. Black Walnut. A handsome tree 20-35 m.high, 6-18 dm. in diameter; crown round, open; bark dark brown with deep furrows; leaf-scars notched at the top; pith light brown. Rich woods, Massachusetts to Minnesota, south to Georgia and Arkansas (Fig. 42).
 
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