Rhynchosia tomentosa , the Twining Snoutbean, is a summer-blooming, native wildflower in the bean family, the Fabaceae. In the Falls Lake area it is most often seen along roadsides and in power lines. There is an extensive colony of R. tomentosa located on both sides of the dirt road to Rockcliff Farm at a point where the power lines cross the road. The plants look very much like their relatives, cultivated soybeans (Glycine max) when not blooming. Both species are small to medium sized, upright plants.
The following photos are of soybeans taken in a farm field. The leaves have a soft, fuzzy look.
Rhynchosia tomentosa is very similar but the leaves have a rough, coarse look to them.
Cultivated soybeans, which are natives of Southeast Asia, have small, bluish-purple flowers. It is possible to drive past fields of blooming soybeans and not notice the inconspicuous flowers that are tucked down in the lower part of the crown. But in Rhynchosia tomentosa, the flowers are bright yellow, protrude from the crown, and are held at the highest point of the plant.
The flower clusters can sometimes be quite large and showy.
R. tomentosa is extremely hardy in hot, dry Piedmont summers and blooms under seemingly adverse conditions. To my knowledge, it has not been adopted for horticultural uses.