Sensitive joint-vetch is an annual plant in the pea family (Fabaceae) that is native to the Eastern United States. Plants typically grow from 3 to 6 feet in a single growing season, although they can grow as tall as 7.8 feet. The stems are single, sometimes branching near the top, with stiff or bristly hairs. The leaves are even-pinnate, 0.8 – 4.7 inches long, with entire, gland-dotted leaflets. Each leaf consists of 30 to 56 leaflets. Leaflets are 0.3 – 1 inch long and 0.08 – 0.16 inches wide. The yellow, irregular flowers are 0.4 – 0.6 inches across, streaked with red, and grow in racemes (elongated inflorescence with stalked flowers). The fruit is a loment with four to 10 one-seeded segments, turning dark brown when ripe. Fruits are 1.2 - 2.8 inches long and shallowly scalloped along one side. 

Sensitive joint-vetch typically grows in the intertidal zone of coastal marshes where plants are flooded twice daily. The species seems to prefer the marsh edge at an elevation near the upper limit of tidal fluctuation, where soils may be mucky, sandy, or gravelly. It is usually found in areas where plant diversity is high (50 species per acre) and annual species predominate. Bare to sparsely vegetated substrates appear to be of critical importance to this plant. As an annual, it requires such microhabitats to establish and grow. Such areas may include areas along rivers with new deposits of soil that have not yet been colonized by perennial species, low swales within extensive marshes, or areas where muskrats have eaten most of the vegetation. It appears to remain at a particular site for a relatively short period of time, and maintains itself by colonizing new, recently disturbed habitats where it may compete successfully among other early-successional species. It is frequently found in the estuarine meander zone of tidal rivers where sediments transported from upriver settle out and extensive marshes are formed. The substrate may be sandy, muddy, gravelly, or peaty. In North Carolina, sensitive joint-vetch is most often found in roadside ditches, often with some connection to nearby brackish marshes.