Crown Vetch is often planted to control erosion on hillsides; it also escapes freely and makes a nuisance of itself. But the bicolored flowers are pretty.
Gray describes the genus (he places it in Coronilla) and the species:
CORONILLA L. Calyx 5-toothed. Standard orbicular; keel incurved. Stamens diadelphous. 9 and 1. Pod terete or 4-angled, jointed; the joints eubrylindric. — Glabrous herbs or shrubs, with pinnate leaves, and the flowers in umbels terminating axillary peduncles. (Diminutive of corona, a crown, alluding to the inflorescence.)
C. vària L. A perennial herb with ascending stems; leaves sessile; leaf lets 15-25, oblong; flowers rose-color; pods coriaceous, 3-7 -jointed, the 4-angled joints 6-8 mm. long. — Roadsides and waste places, N. E. to N. J. (Nat. from Eu.)
A common tree in the forests around Pittsburgh, and also a favorite ornamental in urban and suburban yards. This tree was blooming in early May (later than usual this year) on a wooded hillside in Schenley Park.
Gray describes the genus and the species:
CÉRCIS L. REDBUD. JUDAS TREE. Calyx 6 toothed. Corolla imperfectly papilionaceous; standard smaller than tbe wings and inclosed by them in the bud; the keel petals larger and not united. Stamens 10, distinct, declined. Pod oblong, flat, many-seeded, the upper suture with a winged margin. Embryo straight.—Trees, with rounded heart-shaped simple leaves, caducous stipules, and red-purple flowers in umbel-like clusters along the branches of the last or preceding years, appearing before the leaves, acid to the taste. (The ancient name of the oriental Judas Tree.)
C. canadensis L (REDBUD.) Leaves pointed; pods nearly sessile above the calyx.—Rich soil, N. Y. and N. J. to Fla., w. to s. Ont., e. Neb., and Tex.—A small ornamental tree, often cultivated.
This tree is ubiquitous in southwestern Pennsylvania, so it may come as some surprise to Pittsburghers that we live at the northern end of a native range that is actually very small, mostly in the Appalachians and foothills. The Black Locust has been much planted elsewhere, however, and may easily naturalize itself. It is in many ways an ideal urban tree: it grows fast, tolerates city conditions with no complaints, and has showy clusters of white pea flowers after most of the other flowering trees have stopped blooming. It does, however, have one serious flaw. Mature specimens are brittle, and can easily drop large branches in storms, crushing cars or bringing down power lines. When your power goes out in a thunderstorm, there’s a very good chance you have a Black Locust to blame.
The dangling chains of white pea-shaped flowers are unique among our native trees. Leaves are pinnately compound, with smooth-edged elliptical leaflets. The leaves often turn yellow and begin to drop in August, long before any other trees are even thinking about autumn. Mature trees have rough and shaggy bark, and often show scars of broken branches.
Gray describes the genus and the species (which he spells “Pseudo-Acacia”):
ROBÍNIA L. LOCUST. Calyx short, 5-toothed, slightly 2-lipped. Standard large and rounded, turned back, scarcely longer than the wings and keel. Stamens diadelphous. Pod linear, flat, several-seeded, at length 2-valved. — Trees or shrubs, often with spines for stipules. Leaves odd-pinnate, the ovate or oblong leaflets stipellate. Flowers showy, in hanging axillary racemes. (Named for John Robin, herbalist to Henry IV. of France, and his son Vespasian Robin, who first cultivated the Locust-tree in Europe.)
R. Pseùdo-Acàcia L. (common L., False Acacia.) Branches glabrous or glabrate; racemes slender, loose; flowers white, fragrant; pod smooth.— Along the mts., Pa. to Ga., and in the Ozark Mts. of Mo., Ark., and Okla.; commonly cultivated as an ornamental tree, and for its valuable timber, and naturalized in many places. May, June.