Rhynchosia latifolia Nutt. ex Torr. & A. Gray

Snout Bean

Rhynchosia latifolia plant

Family - Fabaceae/Faboideae

Habit - Perennial herbs with thick, woody rootstocks.

Stems - Prostrate, trailing, twining, sometimes ascending, branched, to 1.5 m, densely pubescent with downward-angled hairs.

Leaves - Alternate, pinnately trifoliate, the petiole to 5 cm. Stipules 2-5 mm, lanceolate, hairy. Leaflets to 7.5 cm, broadly ovate to somewhat rhombic, entire, short-hairy. Undersurface dotted with minute yellow glands and raised venation.

Rhynchosia_latifolia_leaf1.jpgLeaf.

Rhynchosia_latifolia_leaf2.jpgLeaflet abaxial.

Inflorescences - Elongate, relatively open racemes 5-18 cm long, longer than the subtending leaves, with mostly 10-20 flowers, the main stalk 5-20 mm long. Bracts 3-7 mm long, linear to narrowly lanceolate. Flower stalks 1-3 mm long.

Rhynchosia_latifolia_inflorescence.jpgInflorescence.

Calyx - Calyces moderately to densely pubescent with fine, ascending hairs, also dotted with minute, globose resin glands, the tube bell-shaped, shorter than the lobes, more or less 2-lipped, the upper 2 lobes fused to at or above the midpoint, the free portions narrowly triangular-ovate, the lower 3 lobes as long as or slightly shorter than the other lip, narrowly oblong-elliptic to lanceolate, all of the lobes angled or tapered to sharply pointed tips.

Rhynchosia_latifolia_calyx.jpgCalyx and bract.

Rhynchosia_latifolia_calyx2.jpgCalyces.

Flowers - Corollas papilionaceous, yellow to orangish yellow, short-stalked, glabrous or short-hairy on the outer surface. Stamens 10, all of similar lengths, 9 of the filaments fused and 1 free to about the midpoint. Ovary sessile, densely hairy and usually also glandular, the style curved upward, thickened toward the tip, glabrous, the stigma terminal, minute.

Rhynchosia_latifolia_flowers.jpgFlowers.

Rhynchosia_latifolia_corolla.jpgCorolla.

Fruits - Legumes, 15-20 mm long, 7-9 mm wide, flattened, beaked, dark brown at maturity, densely hairy, 2-seeded. Seeds 3-4 mm long, flattened, the surface brown, reddish brown, gray, or black, sometimes with darker mottling, smooth, shiny.

Flowering - June - September.

Habitat - Glades, savannas, dry upland forests, sand prairies, sandy disturbed areas.

Origin - Native to the U.S.

Other info. - This plant is fairly uncommon, found in a few scattered counties in the southern half of the state. Its North American distribution extends in a band from Missouri southward through eastern Texas. The genus is recognized by its gland-dotted leaves, yellow flowers, and small, 2-seeded legumes. Differentiation from the other species which occurs in Missouri, R. difformis, can be challenging.

The genus name is derived from the Greek rhynchus, meaning "beak," referring to the beaks or "snouts" on the fruits.

Photographs taken near Blodgett, Scott County, MO, 8-28-2015 (SRTurner).



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