Phaseolus polystachios (L.) BSP. - Climbing Pea

Phaseolus polystachios plant

Family - Fabaceae

Stems - To +2m long, vining, twining, herbaceous, multiple from the base, branching, pubescent (a few hairs uncinate), angled in younger portions, typically semi-hollow.

Leaves - Alternate, stipulate, trifoliolate, petiolate. Stipules typically spreading, to +/-3mm long, subulate, acute, pubescent abaxially, glabrous adaxially, with ciliolate margins. Petioles to +/-9cm long, (thickened portion at base to 7mm long), puberulent. Petiolules of lateral leaflets to 4mm long, puberulent. Petiolule of terminal leaflet to +/-3cm long. Stiples on all leaflets to 1.5mm long. Lateral leaflets to 12cm long, 7cm broad, ovate but oblique, entire, acuminate. Terminal leaflet to 12cm long, +/-8cm broad, ovate, acuminate, entire. All leaflets deep green above, light green below, pubescent above, with uncinate hairs below which create a "velcro" effect when pressed against cloth and removed quickly.

Phaseolus polystachios leaves

Inflorescence - Axillary racemes or panicles to +15cm long. Axis puberulent with uncinate hairs. Pedicels to 8-9mm long in fruit, sparse puberulent. Each flower subtended by a small bract. Bract attenuate, to +/-3mm long, pubescent as the stipules.

Flowers - Corolla papilionaceous, pinkish, fading to tan. Standard deflexed, to 1cm broad, hooded, glabrous or sparse pubescent externally, glabrous internally. Wings mostly spreading, 8-9mm long, lilac to pinkish. Keels curled back and touching the standard, lilac to pinkish, glabrous, enclosing the fertile floral organs. Stamens diadelphous, the tube white and glabrous. Anthers yellow, .7mm long. Ovary green, glabrous, compressed, 4mm long, subtended by a ringlike nectary, on a short stalk (to 1mm long). Style white, glabrous, 8mm long. Calyx bilabiate, puberulent. Tube to 2mm long, pubescent internally. Upper lip shallow and notched at the apex. Lower lip 3-lobed. Lobes acute, +/-1.2mm long.

Phaseolus polystachios flowers

Flowering - July - September.

Habitat - Low and upland rocky woods, bluffs, slopes, thickets.

Origin - Native to U.S.

Other info. - This attractive species can be found n the lower 1/2 of Missouri. The plant is easy to ID in flower because of its showy flowers and large leaves which stick to clothing and hair.
The fruits of this species are relatively small but can be prepared just as the common bean, P. vulgaris L., which is also native to the U.S.

Photographs taken in the Talladega National Forest, AL., 9-11-05.


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