Psoralea psoralioides (Walt.) Cory - Sampson's Snakeroot
Family - Fabaceae
Stems - To +/-50cm tall, multiple from base, from creeping rhizomes (roots with small nodules), erect to ascending, herbaceous, angled, striate, antrorse strigose (especially on the striations).
Stem and stipule.
Leaves - Alternate, trifoliolate, petiolate, stipulate. Stipules subulate, to 7-8mm long, 2mm broad at the base, antrorse strigose externally and ciliate-margined, glabrous internally, with parallel nerves. Petioles with an adaxial groove, antrorse strigose (sometimes sparse), to +/-7cm long, reduced upward. Petiolules to 6mm long (terminal) 1mm long (lateral), densely pubescent. Leaflets of the lower leaves notched at the apex, oblong-elliptic to narrowly oblanceolate, entire, 3-4cm long, +/-1.5cm broad. Leaflets of the upper leaves lance-linear to oblong-linear, entire, to +/-8cm long, +/-1.2cm broad. All leaflets strigose.
Inflorescence - Axillary pedunculate racemes to +/-4cm long (tall), elongating slightly in fruit. Peduncles to +/-11cm long, antrorse strigose. Pedicels to -2mm long, antrorse strigose. Flowers 1-4 at a node.
Flowers - Corolla lilac (drying tan), papilionaceous. Standard 6mm long, 5mm broad, glabrous, with a darker purple splotch near the base or just a darker purple midvein. Wings and keels basally connate. Keels short, deep purple at the apex, 2.5-3mm long. Wings spreading. Stamens diadelphous, the tube white and glabrous, to 3mm long. Anthers yellow, .1-.2mm long. Ovary green, glabrous, 1.1mm long, with one ovule. Style translucent, 2-3mm long. Calyx 5-lobed (weakly bilabiate), antrorse pubescent, the tube to -1mm long. Lobes acute, the largest to 3mm long. All calyx lobes ciliate-margined, glabrous internally.
Flowering - May - July.
Habitat - On acid soils. Open rocky woods, glades, prairies.
Origin - Native to U.S.
Other info. - This attractive bean can be found mainly in the Ozark region of Missouri. The plant is easy to identify because of its lilac flowers, long-stalked terminal leaflets, thin leaflets, and antrorse strigose stems.
Photographs taken on Bear Mountian, MO., 6-1-03.