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..
[Rhynchosia Lour. Fl. Cochin. 562. 1793.]
Perennial twining, trailing or erect herbs, with pinnately 1-3-foliolate leaves, and yellow mostly axillary and racemose flowers. Leaflets generally punctate with resinous dots, not stipellate. Calyx 4-5-lobed, somewhat 2-lipped. Standard obovate or orbicular, spreading or reflexed. Wings narrow. Keel incurved at the apex or falcate. Stamens diadelphous (9 and 1). Ovary nearly sessile; ovules 2, rarely 1; style filiform. Pod flat, oblong or obliquely orbicular, 2-valved, 1-2-seeded. [Name diminutive of Dolichos.]
About 200 species, natives of warm and temperate regions. In addition to the following, some 12 others occur in the southern States. Type species: Dolicholus minimus (L.) Medic.
Stem twining or trailing.
Racemes shorter than the leaves; flowers 3"-4" long.
Racemes longer than the leaves; flowers about 6" long.
Stem erect, 1°-2 1/2° high.
Leaflets solitary , very broad; plants low, 3'-9' high.
Glycine tomentosa L. Sp. Pl. 754. 1753.
Rhynchosia tomentosa var. volubilis T. & G. Fl. N. A. 1: 285. 1838.
Rhynchosia tomentosa H. & A. Comp. Bot. Mag. I: 23 1835.
D. tomentosus Vail, Bull. Torr. Club 26: 112. 1899.
Trailing or twining, more or less pubescent with spreading hairs, simple or branched, 1°-3° long. Stipules ovate, acute, 2"-4" long, sometimes wanting; petioles shorter than the leaves; leaflets 3, or the lowest leaves I-foliolate, ovate, orbicular or broader than long, obtuse but generally pointed, 1'-2' long; racemes short-peduncled or sessile, 2-8-flowered; flowers 3"-4" long; calyx deeply 4-parted, the upper lobe 2-cleft; pod oblong, acute, pubescent, 8"-9" long, about 3" wide.
In dry sandy soil, Virginia to Florida, west to Texas. May-July.
Rhynchosia latifolia Nutt.; T. & G. Fl. N. A 1. 285. 1838.
Dolicholus latifolius Vail, Bull. Torr. Club 26: 114. 1899.
Softly pubescent, stem angled, trailing or climbing, sometimes 50 long, with a few long branches. Stipules lanceolate, small, or wanting; petioles 1'-3' long; leaflets 3, broadly ovate, or somewhat rhomboid, or the end one orbicular, 1'-3' long, mostly obtuse; racemes elongated, exceeding the leaves, sometimes 1 ° long in fruit, many-flowered; pedicels 1"-2" long; calyx about 6" long, very deeply parted, the segments narrowly lanceolate, acuminate; corolla little longer than the calyx; pod oblong, acute, very pubescent, about 1' long.
In dry soil, Missouri to Louisiana and Texas. May-June.
Trifolium erectum Walt. Fl. Car. 184. 1788.
Rhynchosia erecta DC. Prodr. 2: 384. 1825.
Rhynchosia tomentosa var. erecta T. & G. Fl. N. A. 1: 285. 1838.
D. erectus Vail, Bull. Torr. Club 26: 115. 1899.
Erect, rather stout, simple or slightly branched, velvety-pubescent or tomentose, 1°-2 1/2° high. Stipules linear-lanceolate, acuminate, 2"-3" long; petioles shorter than or equalling the leaves; leaflets 3, oval, ovate or slightly obovate, thick, densely tomentose, especially beneath, obtuse or acute, 1-2' long; racemes 5-15-flowered, sessile or short-peduncled; flowers 3"-5" long; pod oblong, pubescent, 6's" long, about 3" wide.
In dry soil, Delaware to Florida, Tennessee and Louisiana. May-Sept.
Trifolium simplicifolium Walt. Fl. Car. 184. 1788. Rhynchosia renifortnis DC. Prodr. 2: 384. 1825.
Rhynchosia tomentosa var. monophylla T. & G. Fl. N. A. 1: 284. 1838.
Rhynchosia simplicifolia Wood, Bot. & Fl. 96. 1870.
D. simplicifolius Vail, Bull. Torr. Club 26: 114. 1899.
Erect, low, simple, pubescent with spreading hairs, 3'-9' high. Stipules lanceolate, acuminate, 3"-4" long; petioles shorter than or exceeding the leaves; leaflet usually solitary, orbicular or broader, thick, obtuse and rounded or apiculate at the apex, slightly cordate at the base, 1'-2' long (leaflets rarely 3, the lateral ones ovate); racemes rather densely flowered, short-peduncled or sessile; flowers 3"-5" long; pod as in the preceding species.
In dry soil, Virginia to Florida, Tennessee and Louisiana. May-July.