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Habitat and Range. —In its native habitat growing in a variety of soils; rich woods, mountain sides, sterile plains.
Southern Ontario.
Maine,—young trees in the southern sections said to have been produced from self-sown seed (M. L. Fernald); New Hampshire and Vermont,—introduced; Massachusetts,—occasional; Rhode Island,—introduced and fully at home (J. F. Collins); Connecticut,—not reported. Probably sparingly naturalized in many other places in New England.
Spreading by seed southward; indigenous along the western slopes of the Alleghanies in Pennsylvania; south to Georgia and Alabama; west from western New York through southern Ontario (Canada) and Michigan to Nebraska, Kansas, Indian territory, and Texas.
Habit. —A medium-sized tree, reaching a height of 40-60 feet and a trunk diameter of 1-3 feet; becoming a tree of the first magnitude in the river bottoms of Ohio, Kentucky, and Tennessee; trunk dark and straight, the upper branches going off at an acute angle, the lower often horizontal, both trunk and larger branches armed above the axils with stout, sharp-pointed, simple, three-pronged or numerously branched thorns, sometimes clustered in forbidding tangles a foot or two in length; head wide-spreading, very open, rounded or flattish, with extremely delicate, fern-like foliage lying in graceful planes or masses; pods flat and pendent, conspicuous in autumn.
Bark. —Trunk and larger branches a sombre iron gray, deepening on old trees almost to black; yellowish-brown in second year's growth; season's shoots green, marked with short buff, longitudinal lines; branchlets rough-dotted.
Winter Buds and Leaves. —Winter buds minute, in clusters of three or four, the upper the largest. Leaves compound, once to twice pinnate, both forms often in the same leaf, alternate, 6 inches to 1 foot long, rachis abruptly enlarged at base and covering the winter buds: leaflets 18-28, ¾-¼ inches long, about one-third as wide, yellowish-green when unfolding, turning to dark green above, slightly lighter beneath, yellow in autumn; outline lanceolate, oblong to oval, obscurely crenulate-serrate; apex obtuse, scarcely mucronate; base mostly rounded; leafstalks and leaves downy, especially when young.
Inflorescence. —Early June. From lateral or terminal buds on the old wood, in slender, pendent, greenish racemes scarcely distinguishable among the young leaves; sterile and fertile flowers on different trees or on the same tree and even in the same cluster; calyx somewhat campanulate, 3-5-cleft; petals 3-5, somewhat wider than the sepals, and inserted with the 3-10 stamens on the calyx: pistil in sterile flowers abortive or wanting, conspicuous in the fertile flowers. Parts of the flower more or less pubescent, arachnoid-pubescent within, near the base.
Fruit. —Pods dull red, 1-1½ feet long, flat, pendent, and often twisted, containing several flat brown seeds.
Horticultural Value. —Hardy throughout New England, grows in any well-drained soil, but prefers a deep, rich loam; transplants readily, grows rapidly, is long-lived, free from disease, and makes a picturesque object in ornamental plantations, but is objectionable in public places and highly finished grounds on account of the stiff spines, which are a source of danger to pedestrians, and also on account of the long strap-shaped pods, which litter the ground. There is a thornless form which is better adapted than the type for ornamental purposes. The type is sometimes offered in nurseries at a low price by the quantity. Propagated from seed.
| 1. Winter buds. |
| 2. Winter buds with thorns. |
| 3. Flowering branch. |
| 4. Sterile flower, enlarged. |
| 5. Flowering branch, flowers mostly fertile. |
| 6. Fertile flower, enlarged. |
| 7. Fruiting branch. |
| 8. Leaf partially twice pinnate. |
Habitat and Range. —In its native habitat growing upon mountain slopes, along the borders of forests, in rich soils.
Naturalized from Nova Scotia to Ontario.
Maine,—thoroughly at home, forming wooded banks along streams; New Hampshire,—abundant enough to be reckoned among the valuable timber trees; Vermont,—escaped from cultivation in many places; Massachusetts, Rhode Island, and Connecticut,—common in patches and thickets and along the roadsides and fences.
Native from southern Pennsylvania along the mountains to Georgia; west to Iowa and southward.
Habit. —Mostly a small tree, 20-35 feet high, under favorable conditions reaching a height of 50-75 feet; trunk diameter 8 inches to 2 ½ feet; lower branches thrown out horizontally or at a broad angle, forming a few-branched, spreading top, clothed with a tender green, delicate, tremulous foliage, and distinguished in early June by loose, pendulous clusters of white fragrant flowers.
Bark. —Bark of trunk dark, rough and seamy even in young trees, and armed with stout prickles which disappear as the tree matures; in old trees coarsely, deeply, and firmly ridged, not flaky; larger branches a dull brown, rough; branchlets grayish-brown, armed with prickles; season's shoots green, more or less rough-dotted, thin, and often striped.
Winter Buds and Leaves. —Winter buds minute, partially sunken within the leaf-scar. Leaves pinnately compound, alternate; petiole swollen at the base, covering bud of the next season; often with spines in the place of stipules; leaflets 7-21, opposite or scattered, ¾-1¼ inches long, about half as wide, light green; outline ovate or oval-oblong; apex round or obtuse, tipped with a minute point; base truncate, rounded, obtuse or acutish; distinctly short-stalked; stipellate at first.
Inflorescence. —Late May or early June. Showy and abundant, in loose, pendent, axillary racemes; calyx short, bell-shaped, 5-cleft, the two upper segments mostly coherent; corolla shaped like a pea blossom, the upper petal large, side petals obtuse and separate; style and stigma simple.
Fruit. —A smooth, dark brown, flat pod, about 3 inches long, containing several small brown flattish seeds, remaining on the tree throughout the winter.
Horticultural Value. —Hardy throughout New England in all dry, sunny situations, of rapid growth, spreading by underground stems, ordinarily short-lived and subject to serious injury by the attacks of borers. Occasionally procurable in large quantities at a low rate. In Europe there are many horticultural forms, a few of which are occasionally offered in American nurseries. The type is propagated from seed, the forms by grafting.
| 1. Winter buds. |
| 2. Flowering branch. |
| 3. Flower with corolla removed. |
| 4. Fruiting branch. |
This tree appears to be sparingly established in southern Canada and at many points throughout New England.
Common in cultivation and occasionally established through the middle states; native from Virginia along the mountains of North Carolina, South Carolina, and Georgia.
Easily distinguished from R. Pseudacacia by its smaller size, glandular, viscid branchlets, later period of blossoming, and by its more compact, usually upright, scarcely fragrant, rose-colored flower-clusters.