Globally, sensitive jointvetch, Aeschynomene pratensis, isn't a rare plant, but it is in Florida. Extremely rare, in fact.

Sensitive jointvetch has a fairly large native range, but it's only found in Florida among the 50 states, and in only four of the state's 67 counties. It's so rare that environmental officials actually track the number of places where the plant occurs — 11 in all, three in conservation lands. It's so rare that it's state-listed as endangered. The U.S. Fish and Wildlife classifies sensitive jointvetch as "at risk," which carries no real legal weight but relies on the good will of landowners to protect the plant.

And while sensitive jointvetch grows throughout the Caribbean, Central America and South America, the variety found in Florida only grows in Florida. It's demise here reduces the plant's genetic diversity, which could affect the species' viability, ultimately. Sensitive jointvetch also has been introduced to the "old world," meaning generally Europe, Africa and Asia.

The basics: Sensitive jointvetch is a perennial, can reach six feet tall and grows erect rather than sprawling. It has compound leaves about one to three inches long and arranged alternately on the stem. Each leaf has 20 to 26 leaflets, but overall, the foliage is sparse. Like a number of plants in the pea family, the leaves will fold up if touched, the inspiration for its name. The flowers are pea-like, yellow-orange, but can have hints of reds and purples in the petals. Sensitive jointvetch flowers throughout the year. The fruit is a segmented pod. Habitat for the plant includes marl prairies, cypress domes and swales. The four counties in which it's found: Broward, Miami-Dade, Monroe and Collier. Note: the Florida Natural Area inventory does not include Broward in its list of counties where the plant is found.