Macro shot: Flower #02

Mimosa nuttallii, the Catclaw Brier or Sensitive Brier, is a herbaceous perennial legume in the subfamily Mimosoideae. It has a trailing semiwoody vine covered with small recurved prickles that can be painful to bare skin.

The ribbed stems of this plant usually grow to 4 ft. or more and are branched. Plants rarely reach more than 1-2 ft. in height. The frond-like leaves are alternate with prickly stalks. The bipinnate leaf blades are divided into 4-9 pairs of small segments, and these are again divided into 8-15 pairs of tiny leaflets. Leaflets are elliptic, glabrous, with a prominent midrib. Like a few other species of Mimosa (such as M. pudica), the leaves fold up 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 tiny flowers occur in congested bunches. Before they open, they look much like small green bramble fruits. Each individual flower has five minute petals and 8-10 conspicuous stamens. When open, the pink-purple stamens form a globelike cluster at the tip of their leafless stalk. Yellow spores can be often be seen highlighting the tips. The globes are about 0.5 to 0.75" across (about 1.3-2 cm). Flowers and fruits appear from May to September.

The fruit of the Catclaw Brier is a long, slender, rounded pod that has a covering of dense prickles, typically about 3-7 cm (1.2-2.8 in) long.

Habitat includes disturbed areas of sandy or silty soils, roadsides, grasslands, prairies and forest margins. It is known to be very nutritious for livestock, who will seek it out. On rangeland, its absence can also be a good indicator of overgrazing.

Mimosa is a genus of about 400 species of herbs and shrubs, in the subfamily Mimosoideae of the legume family Fabaceae. The generic name is derived from the Greek word μιμος (mimos), meaning "mimic."

There are two species in the genus that are notable^{[citation needed]}. One is Mimosa pudica, because of the way it folds its leaves when touched or exposed to heat. It is native to southern Central and South America but is widely cultivated elsewhere for its curiosity value, both as a houseplant in temperate areas, and outdoors in the tropics. Outdoor cultivation has led to weedy invasion in some areas, notably Hawaii. The other is Mimosa tenuiflora, which is best known for its use in shamanic ayahuasca brews due to the psychedelic drug DMT found in its root bark.