Large deciduous trees. Twigs rather thick, stiff, divergent, sometimes square, or at least compressed at the nodes; pith often obscurely angled. Buds sessile, superposed, with 2 or 3 pairs of scales, those of the terminal bud often lobed. Leaf-scars opposite, half-round to broadly U-shaped; bundle-traces in a curved group; stipule-scars none.
b. Buds brown or red-brown
c. Leaf-scars deeply notched at the top
c. Leaf-scars nearly straight across the top
b Buds blue-black
Twigs acutely 4-angled
1. F. americana L. White Ash. A tree to 25 m. high, bark gray, furrowed into close diamond-shaped areas; twigs gray, glabrous or glabrate (densely pubescent in the var. biltmoreana (Beadle) J. Wright (F. biltmoreana Beadle), Biltmore Ash); leaf-scars deeply notched at the top; buds dark-brown, the terminal broadly ovoid, obtuse. Rich woods, Quebec to Minnesota, south to Florida and Texas (Fig. 277).
2. F. pennsylvanica Marsh. Red Ash. A tree to 30 m. high, with furrowed bark; twigs gray, velvety pubescent (glabrous in the var. subintegerrima (Vahl) Fernald, (F. lanceolata Borkh.), Green Ash); leaf-scars nearly straight across the top; buds rusty brown, pubescent. River-banks, Georgia and Alabama to Texas, north to New England, Quebec, Michigan, Saskatchewan, and Montana (Fig. 278).
3. F. quadrangulata Michx. Blue Ash. A large tree, usually 20-35 m. high; twigs gray, square, or slightly winged, glabrous; buds gray or reddish-brown; leaf-scars obcordate; bundle-traces in a lunate line. Woods, Ontario, Michigan and Wisconsin, south to Alabama and Oklahoma (Fig. 279).
Fig. 277. Fraxinus americana.
Fig. 278. Fraxinus pennsylvanica.
Fig. 279. Fraxinus quadrangulata.
Fig. 280. Fraxinus nigra.
4. F. nigra Marsh. Black Ash. Tree to 25 m. high, with scaly bark; twigs glabrous; leaf-scars nearly orbicular, the bundle-traces in a nearly closed oval; buds blue-black, the terminal broadly ovate-conical. Swamps, Newfoundland to Manitoba, south to West Virginia, Iowa, and North Dakota (Fig. 280 ).