18. INDIGÒFERA, L. Indigo.
Calyx small, equally 5-cleft. Standard roundish, silky outside, wings coherent; keel erect, gibbous or spurred at base. Stamens diadelphous; connective gland-like. Pod 1–several-seeded, septate within between the seeds.—Herbs or shrubs, mostly canescent with appressed hairs fixed by the middle, with odd-pinnate faintly-nerved leaves, and pink or purplish flowers in naked axillary spikes. (So named because some of the species yield the indigo of commerce.)
1. I. leptosépala, Nutt. A perennial herb, ½–2° high; leaflets 5–9, oblanceolate; spikes very loose; pods linear, 6–9 seeded, obtusely 4-angled, reflexed, 1´ long.—Kan. to Tex. and Fla.
19. ROBÍNIA, L. Locust-tree.
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, margined on the seed-bearing edge, at length 2-valved.—Trees or shrubs, often with prickly spines for stipules. Leaves odd-pinnate, the ovate or oblong leaflets stipellate. Flowers showy, in hanging axillary racemes. Base of the leaf-stalks covering the buds of the next year. (Named in honor of John Robin, herbalist to Henry IV. of France, and his son Vespasian Robin, who first cultivated the Locust-tree in Europe.)
1. R. Pseudacàcia, L. (Common Locust or False Acacia.) Branches naked; racemes slender, loose; flowers white, fragrant; pod smooth.—S. Penn. to Ind., Iowa, and southward. Commonly cultivated as an ornamental tree, and for its valuable timber; naturalized in many places. June.
2. R. viscòsa, Vent. (Clammy L.) Branchlets and leaf-stalks clammy; flowers crowded in oblong racemes, tinged with rose-color, nearly inodorous; pod glandular-hispid.—Va. to N. C. and Ga., in the mountains. Cultivated, like the last, and often escaped. June.
3. R. híspida, L. (Bristly L. or Rose Acacia.) Shrub 3–8° high; branchlets and stalks bristly; flowers large and deep rose-color, inodorous; pods glandular-hispid.—Varies with less bristly or nearly naked branchlets; also with smaller flowers, etc.—Mts. of Va. to N. C. and Ga. May, June.
20. WISTÀRIA, Nutt.
Calyx campanulate, somewhat 2-lipped; upper lip of 2 short teeth, the lower of 3 longer ones. Standard roundish, large, turned back, with 2 callosities at its base; keel scythe-shaped; wings doubly auricled at the base. Stamens diadelphous. Pods elongated, thickish, knobby, stipitate, many-seeded, at length 2-valved. Seeds large.—Woody twiners, climbing high, with minute stipules, pinnate leaves of 9–13 ovate-lanceolate leaflets, with or without minute stipels, and dense racemes of large and showy lilac-purple flowers. (Dedicated to the late Professor Wistar, of Philadelphia.)
1. W. frutéscens, Poir. Downy or smoothish when old; wings of the corolla with one short auricle and an awl-shaped one as long as the claw.—Alluvial grounds, Va. to Fla., west to S. Ind., Kan. and La. May.—Sometimes cultivated for ornament, as is the still handsomer Chinese species.
21. ASTRÁGALUS, Tourn. Milk-Vetch.
Calyx 5-toothed. Corolla usually long and narrow; standard narrow, equalling or exceeding the wings and blunt keel, its sides reflexed or spreading. Stamens diadelphous. Pod several–many-seeded, various, mostly turgid, one or both sutures usually projecting into the cell, either slightly or so as to divide the cavity lengthwise into two.—Chiefly herbs (ours perennials), with odd-pinnate leaves and spiked or racemed flowers. Mature pods are usually necessary for certain identification of the species. (The ancient Greek name of a leguminous plant, as also of the ankle-bone; but the connection between the two is past all guess.)
I. Pod turgid, completely or imperfectly 2-celled by the intrusion of the dorsal suture, the ventral suture being not at all or less deeply inflexed.—Astragalus proper.
[*] Pod plum-shaped, succulent, becoming thick and fleshy, indehiscent, not stipitute, completely 2-celled.
1. A. caryocárpus, Ker. (Ground Plum.) Pale and minutely appressed-pubescent; leaflets narrowly oblong; flowers in a short spike-like raceme; corolla violet-purple; fruit glabrous, ovate-globular, more or less pointed, about {2/3}´ in diameter, very thick-walled, cellular or corky when dry.—Sask. and Minn. to Mo., Col., and Tex. May.
2. A. Mexicànus, A. DC. Smoother, or pubescent with looser hairs, larger; leaflets roundish, obovate, or oblong; flowers larger (10–12´´ long); calyx softly hairy; corolla cream-color, bluish only at the tip; fruit globular, very obtuse and pointless, 1´ or more in diameter; otherwise like the last.—Prairies and open plains, Ill. to Kan., south to Tex. The unripe fruits of both resemble green plums—whence the popular name—and are eaten, raw or cooked, by travellers.
3. A. Platténsis, Nutt. Loosely villous; stipules conspicuous; leaflets oblong, often glabrous above; flowers crowded in a short spike or oblong head, cream-color often tinged or tipped with purple; fruit ovate, pointed, and with the calyx villous.—Gravelly or sandy banks, Minn. to Ind. and Ala., west to Col. and Tex.—Var. Tennesseénsis, Gray, has the pod oblong and slightly curved, and much less fleshy. May.
[*][*] Pod dry, coriaceous, cartilaginous or membranous, dehiscent.
[+] Pod completely 2-celled, sessile.
4. A. mollíssimus, Torr. Stout, decumbent, densely silky-villous throughout and tomentose; leaflets 19–29, ovate-oblong; peduncles elongated; spikes dense, with rather large violet flowers (6–12´´ long); pod narrow-oblong (5–9´´ long), glabrous, somewhat obcompressed and sulcate at both sutures, at length incurved.—Neb. to Kan. and Tex., west to Col. The most common "loco"-plant, and said to be very poisonous to cattle.
5. A. Canadénsis, L. Tall and erect (1–4° high), somewhat pubescent or glabrate; leaflets 21–27, oblong; flowers greenish cream-color, very numerous, in long dense spikes, pods crowded, oblong (6´´ long), glabrous, terete, scarcely sulcate and only on the back, nearly straight.—River-banks, western N. Y. to N. Ga., and far westward.
6. A. adsúrgens, Pall. Ascending or decumbent (4–18´ high), cinereous with minute appressed pubescence or glabrate; leaflets about 21, narrowly or linear-oblong; spike dense, with medium-sized pale or purplish flowers; pubescence of calyx appressed; pod oblong (4–5´´ long), finely pubescent, triangular-compressed, with a deep dorsal furrow, straight.—Red River valley, Minn., to W. Kan., and westward. (Asia.)
7. A. hypoglóttis, L. Slender (6´–2° long), diffusely procumbent or ascending, with a rather loose pubescence or nearly glabrous; leaflets 15–21, oblong, obtuse or retuse; flowers violet, capitate; calyx loosely pubescent; pod as in the last, but ovate and silky-villous.—Red River valley, Minn., to central Kan. and westward.
[+][+] Pod not completely 2-celled.
[++] Pod stipitate, pendent.
8. A. alpìnus, L. Diffuse (6–12´ high), smooth or slightly hairy; leaflets 13–25; flowers violet-purple, or at least the keel tipped with violet or blue; calyx campanulate; pod narrowly oblong, short-acuminate, black-pubescent, triangular-turgid, deeply grooved on the back, straight or curved, its stipe usually rather exceeding the calyx.—Rocky banks, Lab. to Maine and N. Vt.
9. A. Robbínsii, Gray. Nearly smooth and erect (1° high), slender; leaflets 7–11; calyx more oblong; flowers white; pod oblong (6´´ long), obtuse or acutish, minutely darkish-pubescent, somewhat laterally compressed, not dorsally