Family, Mallow. Color, yellow. Calyx, 5-cleft. Petals and styles, 5. Fruit, of 5 carpels united, each becoming 2-beaked at the top. Leaves, linear or lance-shaped, on petioles, toothed.

A low, branched plant getting its name from a spine-like protuberance found at the base of some of the leaves. An importation from the tropics, this plant is now found growing in waste fields of southern New York and to the westward and southward.