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..
Hedysarum rigidum Ell. Bot. S. C. and Ga. 2: 215.
1824. Desmodium rigidum DC. Prodr. 2: 330. 1825. Meibomia rigida Kuntze, Rev. Gen. Pl. 198. 1891.
Erect or ascending, rather rigid, finely uncinate-pubescent, 2°-3° high. Stipules small, lanceolate, deciduous; leaves petioled; leaflets ovate, oblong or oval, obtuse, thickish, scabrous above, pubescent, especially along the veins beneath, 1-2' long; racemes terminal, compound; flowers very small, 1"-2" long, purplish; upper lobe of the calyx entire or minutely 2-toothed, the 3 lower ones slender; loment sessile in the calyx, 1-3-jointed, the joints obliquely ovate, rounded on the back, uncinate-pubescent, about 1 1/2" long.
In dry soil, New Hampshire to Florida, Michigan, Nebraska, Kansas, Arkansas and Louisiana. July - Oct
Hedysarum marylandicum L. Sp. Pl. 748. 1753.
Desmodium marylandicum Boott.; Darl. Fl. Cestr. 412. 1837.
Meibomia marylandica Kuntze, Rev. Gen. Pl. 198. 1891.
Erect or ascending, glabrous, or rarely with a few scattered hairs, slender, 2°-3° high. Stipules subulate, deciduous or persistent; petioles 3"-6" long; leaves crowded; leaflets 3"-12" long, ovate or nearly orbicular, obtuse, glabrous on both sides, the lateral often subcordate; upper lobe of the calyx emarginate or minutely 2-toothed; racemes panicled; corolla purplish, very small, 1"-2" long; loment sessile in the calyx or nearly so, 1-3-jointed, the joints small, obliquely oval or semi-orbicular.
Hedysarum obtusum Muhl.; Willd. Sp. Pl. 3: 1190. 1803. Hedysarum ciliare Muhl.; Willd. Sp. Pl. 3: 1196. 1803. Desmodium ciliare DC. Prodr. 2: 329. 1825. Meibomia obtusa Vail, Bull. Torr. Club 19: 115. 1892.
Erect or ascending, bushy, 1°-3° high, pubescent. Stipules subulate, deciduous; leaves crowded; petioles ciliate, shorter than the leaflets; leaflets broadly ovate or oval, obtuse, somewhat coriaceous, more or less pubescent on both sides, ciliate, 6"-12" long; racemes terminal, compound or simple, uncinate-pubescent; upper lobe of the calyx entire or minutely 2-toothed, the lower ones acute; flowers 1 "-2" long; loment 2-3-jointed, the joints obliquely oval; stipe not exceeding the calyx-lobes.
Dry soil, Ontario to Massachusetts and Florida, west to Michigan, Missouri, Arkansas and Texas. Cuba. July-Oct.