- Herbaceous, erect to reclining or vining, green, puberulent and very sparse pilose, to 60cm long, from a big taproot.
- Alternate, trifoliolate, stipulate, petiolate. Stipules to 5mm long, 2mm broad, subulate-ovate, acute, spreading, sparse ciliate-margined. Swollen portion at base of petiole to 2.1mm long. Petiole pubescent as stem. Stiples needlelike, 2mm long. Petiolules of terminal leaflet to 2.5mm long, pubescent as the stem. Leaflets lance-ovate, to 7cm long, 3cm broad, deep green adaxially, bluish-green below, mucronate, very sparse pubescent.
- Single axillary flowers. Pedicel jointed in upper 2/3, with a pair of opposing bracts at joint. Bracts to 4.5mm long, 1.5mm broad, green, glabrous. Pedicel minutely pubescent(sparse), to 8mm long in flower.
- Corolla resupinate, papilionaceous. The standard lilac internally with a pale yellow splotch near the apex and purple spotting basally in the center, notched at apex, to -5cm long, -4cm broad, glabrous, pale lilac to whitish externally. Wing petals purplish(lilac) at apex, +/-4cm long, apically connate and adnate to the keel petals. Keel petals clawed and white. Stamens diadelphous, the tube white and glabrous, to 3cm long. Ovary stalked. Stalk to 6mm long, green, tomentoulose. Ovary slightly compressed, 8mm long, tomentoulose. Style white, upcurved, to 1.5cm long, flattened, with a beard of hairs adaxially.
Calyx bilabiate, the upper lip single-lobed. The lobe notched at the apex creating two shallow lobes, the lobes acute and 4mm long. The lower lip 3-lobed. Lobes triangular, acuminate, entire, to +/-7mm long. The central lobe less broad than the lateral lobes. all the lobes ciliate-margined. Calyx tube cylindric, green, to 1.5cm long, 7-8mm in diameter, glabrous internally, with a few sparse hairs externally but mostly glabrous. Calyx subtended by a pair of opposite bracts. Bracts to 4.5mm long, 1.5mm broad, green, glabrous.
Fruit to +/-4cm long, slightly compressed, glabrous, beaked, with a stalk to +1cm long.
- May - September.
- Upland rocky woods with acid soils, sandstone glades, ravines, ridges, stream openings.
- Native to U.S.
- This popular and striking species can be found in the southern 1/4 of Missouri. The flowers of this species are quite large. The plant is commonly called "Butterfly Pea" not because it is a good butterfly attracting species but because of its big flowers which are butterfly-shaped (papilionaceous).
This species would make a good ornamental but does not transplant well and is "picky" about where it will grow.
Photographs taken at the Current River Conservation Area, Reynolds County, MO., 8-2-01.