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..
Twining or trailing herbaceous vines, rarely erect, mostly pubescent, with pinnately 3-foliolate stipellate leaves, and pink-purple or nearly white flowers capitate at the ends of long axillary peduncles. Calyx as in Phaseolus. Standard nearly orbicular;wings mostly obovate; keel strongly curved. Stamens diadelphous (9 and 1). Style longitudinally bearded, bent. Pod linear, nearly terete, or somewhat compressed, usually straight, few-several-seeded, tipped by the persistent style. Seeds truncate at the ends, more or less pubescent or mealy. [Greek, bent style.]
An American genus, of about 6 species. Type species: Strophostyles angulosa Ell.
Leaflets mainly lobed, 1' - 2' long; pod 2'-3' long; root annual.
Leaflets mainly entire, 1/2'-1 1/2' long; pod 1' - 2' long.
Flowers several, about 6" long; root perennial.
Flowers few, about 3" long; root annual.
Phaseolus helvolus L. Sp. Pl. 724. 1753. Phaseolus angulosus Ort. Nov. Pl. 24. 1797. Phaseolus diversifolius Pers. Syn. 2: 296. 1807. Strophostyles angulosa Ell. Bot. S. C. 2: 229. 1822. S. helvola Britton; Britt. & Brown, 111. Fl. 2: 338. 1897.
Prostrate or low-twining, rather rough-pubescent, branched at the base, 2°-8° long, rarely erect and 10'-2o' high. Root annual; stipules narrowly lanceolate, 1"-2" long; leaflets broadly ovate, obtuse or acute at the apex, rounded at the base, thickish, generally more or less obtusely lobed, sometimes entire, 1'-2' long, the lower ones often inequilateral; peduncles axillary, exceeding the petioles; flowers 3-10, sessile, capitate; corolla greenish-purple, 4"-6" long; keel slender, curved; pod sessile, linear, nearly terete, slightly pubescent, 2'-3' long; seeds oblong, pubescent, 2 1/2"-3 1/2" long.
In sandy soil, Quebec to Massachusetts, Florida, Ontario, South Dakota, Kansas and Texas. July-Oct.
Strophostyles missouriènsis (S. Wats.) Small, regarded as a variety of this species in our first edition, differs by being a longer vine, climbing over trees and bushes, its leaflets nearly entire and its seeds slightly larger. It ranges from Virginia to Illinois and Kansas.
Glycine umbellata Muhl.; Willd. Sp. Pl. 3: 1058. 1803.
Strophostyles peduncularis Ell. Bot. S. C. 2: 230. 1822.
Phaseolus helvolus T. & G. Fl. N. A. 1: 280. 1838. Not L. 1753.
S. timbellata Britton; Britt. & Brown, 111. Fl. 2: 339. 1907.
Root perennial; stems slender, trailing, branching, more or less pubescent with retrorse hairs, 1°-5° long. Stipules ovate-lanceolate, 1"-2" long; leaflets ovate, lanceolate or oblong, obtuse or acutish at the apex, rounded at the base, sparingly pubescent, entire, or rarely with 1 or 2 shallow lobes; peduncles generally much longer than the leaves; flowers several, pink, fading yellowish, capitate-umbellate, about 6" long, similar to those of the preceding species; pedicels 1/2"-1" long; pod linear, straight, little compressed, sessile, 1'-2' long, 2" wide, sparingly pubescent; seeds mealy-pubescent, 1 1/2"-2" long.
In sandy soil, Long Island to Florida, Indiana, Arkansas and Texas. July-Sept.