Desmodium ×humifusum
Bot. North. Middle States, 86. 1833. (as species)
Herbs, perennial. Stems prostrate, 100–200(–300) cm, sparsely to densely patent-pubescent and uncinate-puberulent. Leaves trifoliolate; stipules often caducous, sometimes persistent, ovate or narrowly ovate, 4.5–8 mm; petiole 28–50 mm; leaflet blades ovate or rhombic-ovate, lateral veins inconspicuous, arcuate along margin, apex acute or obtuse, surfaces sparsely strigose; terminal blade 30–70 × 20–50 mm, length 1.4–2 times width. Inflorescences lax-flowered, ascending, terminal and branched, also axillary and unbranched; rachis uncinate-puberulent; primary bracts caducous, ovate, 3–4 mm. Pedicels 7–9 mm. Flowers: calyx 2.5–3.5 mm, uncinate-puberulent, tube 1 mm; abaxial lobes 2 mm, lateral lobes 1.5 mm; corolla purple, 8–9.5 mm. Loments: sutures obtusely dentate abaxially, sinuate adaxially; connections adaxial, 1/4–1/3 as broad as segments; segments 3 or 4, deltate-rhombic, 6–8 × 4–5 mm, obtusely angled abaxially, straight or slightly convex adaxially, uncinate-pubescent; stipe 2 mm.
Phenology: Flowering summer–fall.
Habitat: Woodland openings and edges, powerline cuts, near exposed limestone.
Elevation: 0–300 m.
Distribution
Conn., Del., Ind., Md., Mass., Mo., N.J., N.Y., Pa.
Discussion
Desmodium ×humifusum had been recognized as a species, but J. A. Raveill (2002) confirmed a hybrid origin from D. paniculatum and D. rotundifolium by allozyme electrophoresis. Desmodium × humifusum is likely to occur more widely than reported. It is in the Center for Plant Conservation’s National Collection of Endangered Plants as D. humifusum.
Selected References
None.