Tephrosia virginiana (L.) Pers.

Goat's Rue

Tephrosia virginiana plant

Family - Fabaceae

Stems - To 50cm tall, from caudex and long woody roots, multiple from base, herbaceous, densely villous to hirsute, erect to reclining or sprawling, often reddish-purple, simple to few branching.

Tephrosia virginiana stem

Leaves - Alternate, odd-pinnate, stipulate. Stipules to 11mm long. Leaflets opposite to subopposite, with short petiolules or sessile, 11-25, oblong-elliptic, mucronate to apiculate, to 2.5cm long, 1cm broad, entire, sericeous below, pubescent above, with prominent midrib. Terminal leaflet typically emarginate, cuneate, slightly smaller than lateral leaflets.

Tephrosia virginiana leafAdaxial leaf surface.

Tephrosia virginiana leafAbaxial leaf surface.

Inflorescence - Terminal compact racemes to -10cm long (tall). Pedicels to 1cm long in flower, hirsute to densely villous. Each flower subtended by a bract to +1cm long. Bracts pubescent to villous.

Tephrosia virginiana inflorescenceInflorescence.

Flowers - Corolla papilionaceous, bicolored, to +1.5cm long and broad. Standard yellow to tannish, 1.5cm broad, +1.5cm long, with slight purple mottling at base, densely pubescent externally, glabrous internally. Keel and wings pink to rose, to 1.5cm long, glabrous. Stamens monodelphous(but sometimes appearing diadelphous), the tube(filaments) glabrous and white. Ovary canescent, 8-9mm long. Style upcurved, bearded, green, 8mm long. Calyx tube purplish above, green below, canescent externally, glabrous internally, to +3mm long. Upper lip 2-lobed. Lobes acuminate or attenuate, to 4mm long. Lower lip 3-lobed. Lobes acuminate to attenuate, to 6mm long. Fruit to +5cm long, 5mm broad, compressed, brownish with some black, canescent.

Tephrosia virginiana calyxCalyx.

Tephrosia virginiana flowerFlower close-up.

Flowering - May - August.

Habitat - Rocky open woods, glades, prairies.

Origin - Native to U.S.

Other info. - T. virginiana is a very striking and important plant. The large roots contain nitrogen fixing bacteria and also rotenone, the latter being used as an insecticide and fish poison. Traditionally, the plant had been used to treat many ailments such as tuberculosis, rheumatism, and bladder troubles. The plant has also been studied in cancer research.
Steyermark stated that the plant "does not transplant successfully" and doesn't really take from seed either because of the special relationships and requirements the plant has with the acid soil in which it grows.
The pubescence of the leaves can vary from glabrous to sericeous above.
The plant is common throughout Missouri but is apparently absent from the northwest corner of the state.

Photographs taken at the Current River Conservation Area, Reynolds County, MO., 6-13-01, and in Alley Spring, MO., 6-3-03.