A spiny Fabaceae, Mimosa pigra inhabits the margins of wetlands and is touch-sensitive. It’s flowers form a small, ball-like inflorescence and develop into seed-filled pods when fruiting. Among other characteristics, M. pigra is told from M. dormiens, another common spiny plant at wetland margins, in having curved spines along leaf rachis and more erect stems.
I never got the chance to photograph this wetland plant before – Ipomoea carnea. It occurs in small, thick, patches, which emerge in relatively shallow areas, and has a thick, woody stem, particularly at the base.