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..
Perennial herbs, mainly with some villous or viscid pubescence, 3-foliolate leaves, and yellow terminal or axillary spicate or capitate flowers. Calyx deciduous, its tube narrow, its teeth membranous, the 4 upper ones more or less united. Petals and stamens inserted at or near the summit of the tube; standard orbicular; wings oblong; keel curved, beaked. Stamens monadelphous; anthers alternately longer and shorter. Ovary nearly sessile; ovules 2-3; style filiform. Pod sessile, flattened, 1-2-jointed, reticulate, dehiscent at the summit. [Greek, column-flower, alluding to the column-like calyx-tube.]
About 30 species, natives of warm and temperate regions. Besides the following, another occurs in the southern States. Type species: Stylosanthes procumbens Sw.
Leaflets oblong-linear to oblanceolate; floral bracts entire.
Leaflets elliptic to obovate; floral bracts deeply cleft.
Trifolium biflorum L. Sp. Pl. 773. 1753.
Stylosanthes elatior Sw. Svensk. Acad. Handl. 1789: 296. pl. 2. f. 2. 1789.
Stylosanthes biflora B.S.P. Prel. Cat. N. Y. 13. 1888.
Wiry, branched from the base and often also above, stems ascending, erect or spreading, villous-pubescent or glabrate, 6'-24' long. Stipules sheathing the stem, linear-filiform above; leaves short-petioled; leaflets 3, oblong, linear-oblong or oblanceolate, acute or acutish and mucronate at the apex, narrowed or cuneate at the base, 6"-18" long, 1 1/2"-2" wide, strongly veined, the terminal one stalked; upper bracts entire; flowers few, mainly terminal, sessile or nearly so, yellow, ciliate-bracted, 3"-4" long; pod obovate or suborbicular, pubescent, about 2" long, of 1 perfect and 1 abortive joint.
In dry soil, southeastern New York to Florida, west to Indiana, Kansas, Tennessee, Louisiana and Texas. June-Sept.
Stylosanthes riparia Kearney, Bull. Torr. Club 24: 565. 1897.
Stems decumbent, or ascending, 3'-12' long, usually with a tomentose line on the elongated internodes. Stipules sheathing, subulate above; petioles pubescent; leaflets elliptic to obovate-cuneate, the terminal one 5"-9" long, the lateral ones somewhat smaller; spikes terminal, about 6-flowered, with only 1 or 2 perfect flowers; calyx-tube conspicuously veined, about 2" long; vexillum proportionately longer than in S. biflora; floral bracts usually deeply cleft to the middle, or beyond, 2-nerved; upper (perfect) segment of the pod nearly twice as broad as in S. biflora.
Herbs, with digitately 4-foliolate or 2-foliolate petioled leaves, the leaflets not stipellate, the stipules small or foliaceous, sagittate. Flowers yellow in our species, small, interruptedly spicate, large-bracted, sessile, rarely solitary, the spikes axillary and terminal, peduncled. Bracts 2 together, nearly enclosing the flower. Calyx 2-lipped, 5-lobed, its tube short. Standard nearly orbicular, clawed; wings oblique; keel incurved. Stamens monadelphous; anthers alternately longer and shorter. Ovary sessile; ovules several; style very slender. Loment flat, several-jointed. [In honor of Johann Zorn, a, German apothecary.]
About 12 species, all natives of America, 2 of them naturalized in the warmer regions of the Old World, the following typical. Besides the following, another occurs in the southwestern states.
Anonymos bracteata Walt. Fl. Car. 181. 1788. Zornia bracteata Gmel. Syst. 2: 1096. 1791. Zornia tetraphylla Michx. Fl. Bor.. Am. 2: 76. 1803.
Perennial by a long woody root, glabrous or sparingly finely pubescent; stems wiry, prostrate, 1°-2° long. Stipules about 3" long; petioles 1/2'-1' long, slender; leaflets 4, oblong, lanceolate, on oblong-obovate, acute at both ends, 1/2'-1' long, or those of the lower leaves obtuse at the apex and shorter; peduncles longer than the petioles; spikes several-flowered, much interrupted in fruit, 2'-4' long; bracts ovate or broadly oval, 3"-5" long, acute or acutish; pod 3-5-jointed, the joints oval, 1 1/2"-2" long, densely spinulose.
In dry sandy soil, southeastern Virginia to Florida, Texas and Mexico. May-Aug.
Arachis hypogaéa L., the pea-nut, is occasionally seen as a waif, not permanently established.