This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Herbs, or rarely shrubs, often canescent with hairs affixed by the middle, with odd-pinnate leaves, small stipules, and pink or purple spicate or racemose flowers. Calyx-teeth oblique, nearly equal, or the lower longer. Standard ovate or orbicular, sessile or clawed; wings oblong; keel erect, somewhat gibbous, or spurred Stamens mainly monadelphous; anthers all alike. Ovary sessile or nearly so, 1-00-ovuled; style slender. Pod linear, 4-angled (in our species), septate between the seeds. [Name from the yield of indigo by some species.]
About 275 species. natives of warm and temperate regions. In addition to the following, some 7 others occur in the southern and southwestern United States. Type species: Indigofera tinctoria L.
Indigofera lettosepala Nutt.; T. & G. Fl. N. A. 1: 298. 1838.
Perennial decumbent, cinereous-pubescent, slender, branching, 6'-24' long. Leaves short-petioled; leaflets 5-9, oblanceolate or oblong-linear, 3"-12" long, 1-3" wide, obtuse and often mucron-ulate at the apex, narrowed or cuneate at the base, short-stalked; spikes peduncled, loosely few-flowered; flowers pink or purplish, about 3" long; calyx-teeth subulate, equal; pods linear, acute, obtusely 4-angled, sessile in the calyx, 8"-12" long, 1" thick, re-flexed at maturity.
21. CRÁCCA L. Sp. Pl. 752. 1753.
[Tephrosia Pers. Syn. 2: 328. 1807.]
Herbs, sometimes slightly shrubby, with odd-pinnate not punctate leaves, and purple red or white flowers in terminal or lateral racemes or short clusters. Stipules small. Leaflets entire. Calyx-teeth usually nearly equal. Petals all clawed. Standard orbicular or broadly ovate; wings obliquely obovate or oblong; keel curved. Stamens monadelphous or diadel-phous; anthers all alike. Ovary sessile; ovules several or many. Pod linear, flat, 2-valved, several-seeded, continuous, or with membranous septa between the seeds. [Latin, vetch.]
About 120 species, mainly natives of warm and tropical regions. Besides the following, eleven species occur in the southern and southwestern United States. Type species: Cracca villosa L.
Raceme terminal, dense, nearly sessile, many-flowered.
Peduncles lateral and terminal, elongated, few-flowered.
Villous; flowers in an interrupted spike or raceme.
Pubescent; peduncles few-flowered near the summit.