The leaves immediately fold up when disturbed. In Jamaica the plant is also known as "Shame old lady."
This refers to the alledged habit of "Old ladies" to fold up their skirts to hide their undergarments.
Sometimes grown as a novelty plant the folding action is caused by expulsion of water sap from "bladders" in the leaf axils.
The branches are thorny and the thorns are exposed after the leaves have folded. The folding action is thought to be a protective evolutionary trait.