Mimosa pudica L.

• Authority

  Britton, Nathaniel L. Flora Borinqueña.

• Family

  Mimosaceae

• Scientific Name

  Mimosa pudica L.

• Description

  Species Description - First observation of this little plant is surprising, and it always remains fascinating, as a remarkable, unusual illustration of extreme sensitivism of vegetation; animal sensitivism is so nearly universal that we regard it as a matter of course, but in plants is rare. It is a low, prickly, slightly woody herb, with slender-stalked, twice compound leaves, the leaflets small and narrow, and small, pink flowers, in stalked, axillary heads. If shocked, or even touched, the leaves, and their divisions, are instantly deflexed, and the leaflets fold together; this sensitiveness is inherent in small structures called pulvini at the bases of the leaf-stalks and those of the leaf-divisions. The plant soon recovers from shock and regains its normal aspect, whence the popular Spanish name. The species is distributed nearly throughout tropical America, and has been introduced into tropical Asia and Australasia; it is common in fields and on banks at lower and middle altitudes in Porto Rico, ascending to at least 500 meters, and grows also on Vieques Island; it is the only true Mimosa in our Flora; Sensitiva is another Spanish name. Mimosa (Greek, referring to the sensitive leaves of some species) is a Linnaean genus comprising some 300 species, natives of tropical and temperate regions. They are herbs, or shrubs, rarely small trees, with twice compound leaves, and small, regular, 4-parted, or 5-parted flowers, in stalked, axillary heads or spikes. The calyx has short teeth; the petals are more or less united towards the base; the stamens are as many, or twice as many, as the petals, separate from each other, with slender filaments; the ovary contains from 2 to many ovules, the style is slender, topped by the small stigma. The narrow, flat pod is transversely jointed. Mimosa pudica (shamefaced, in allusion to sensitiveness) is branched, from 20 to 50 centimeters long, is armed with somewhat curved prickles from 2 to 4 millimeters long, and sometimes long-hairy. The leafstalks are from 2 to 6 centimeters long, the leaf divisions 1 pair, or 2, approximate pairs, about 6 centimeters long, or shorter; there are from 6 to 25 pairs of thin leaflets on each leaf-division, from 6 to 10 millimeters long and 1.5 or 2 millimeters wide. The ovoid flower-heads are borne on stalks from 1 to 2 centimeters long; there are 4 petals; the 4 stamens are pink, fading white. The pods are from 10 to 15 millimeters long, about 3 millimeters wide, from 2-jointed to 5-jointed, constricted at the joints, their margins armed with straight prickles.

• Discussion

  Morivivi Sensitive Plant Mimosa Family Mimosa pudica Linnaeus, Species Plantarum 518. 1753.