Fourvalve mimosa

Mimosa quadrivalvis, the fourvalve mimosa or sensitive briar, is a perennial herbaceous to subwoody vine in the Fabaceae native to dry prairies, open woods, and sandy roadsides across the south-central and southeastern United States, with closely related forms extending into Mexico and Central America. Plants produce trailing or sprawling stems 0.5 to 2 metres long that are armed with numerous short, recurved prickles. The alternate leaves are bipinnately compound with 4 to 8 pairs of pinnae, each pinna bearing 8 to 16 pairs of small, oblong leaflets 2 to 5 mm long; the leaflets close rapidly when touched (seismonastic movement). Globose pink to lavender flowerheads 1.5 to 2.5 cm across with prominent projecting pink filaments and yellow anthers are borne on long axillary peduncles from late spring through summer. The fruit is a slender, prickly, oblong-linear legume 4 to 8 cm long that splits at maturity into four valves, leaving a persistent central frame — the trait that gives the species its specific epithet.