Family - Fabaceae

Stems - Sprawling to clambering or climbing(by means of tendrils on leaves), glabrous to sparse pubescent, carinate to angled, herbaceous, from taproot.

Stem.

Leaves - Alternate, stipulate, even-pinnate, terminating with branched tendrils. Stipules 1cm long, 2mm broad, often with a small lateral lobe, ciliate margined, appressed pubescent. Leaflets in +/-8 pairs, subopposite, oblong to elliptic-oblong, entire, mucronate, to 2.5cm long, 6mm broad, with sparse antrorse appressed pubescence. Petiolules to 1mm long, sparse pilose.

Inflorescence - Axillary pedunculate racemes to +/-10cm long. Peduncle glabrous to sparse pubescent. Pedicels 1mm long, attached to lower portion of calyx tube. Flowers nodding and secund.

Flowers - Corolla glabrous, 1.5-2cm long, papilionaceous, typically purplish or rarely white. Keel and wing petals often lighter than standard. Stamens 10. diadelphous, glabrous. Ovary glabrous, compressed, 5mm long, green. Style pubescent, 1.5-2mm long. Calyx weakly bilabiate, purplish. Tube 3mm long, glabrous to sparse appressed pubescent. Upper lip 2-lobed. Lobes acute, 1.1mm long. Lower lip 3-lobed. Lobes linear. Central lobe to 3mm long. Fruit compressed, glabrous, +/-3.5cm long, 1cm broad.

Calyx close-up.

Fruit.

Flowering - May - October.

Habitat - Open ground, prairies, roadsides, railroads.

Origin - Native to Europe.

Other info. - This species is very weedy in Missouri. It strongly resembles another weed, V. villosa Roth, but the latter has very villous stems and leaves, and flowers which are more of a bluish color. Some authors don't distinguish between these two species, lumping them both under V. villosa.
Here is a look at the white form of V. dasycarpa:

Photographs taken off Hwy 19 near Salem, MO., 5-18-03.