Mimosa nuttallii

Mimosa nuttallii, the Nuttall's sensitive-briar, catclaw brier, or sensitive brier, is an herbaceous perennial legume in the subfamily Mimosoideae native to the central United States. It has a trailing semi-woody vine covered with small recurved prickles that can be painful to bare skin. The ribbed stems of this plant usually grow to 4 ft (1.2 m) or more and are branched. Plants rarely reach more than 1–2 ft (0.3–0.6 m) in height. The frond-like leaves are alternate with prickly stalks. The bipinnate leaf blades are divided into four to nine pairs of small segments, and these are again divided into 8–15 pairs of tiny leaflets. Leaflets are elliptic and glabrous with a prominent midrib. Like a few other species of Mimosa (such as M. pudica), the leaves exhibit nyctinastic movement, folding up quickly when touched or disturbed. It is also said that the roots of M. nuttallii give off an acrid, garlic-like smell when disturbed. This may be an additional defense mechanism of the plant. The......read more on Wikipedia.