On the stems, there is a single spine below each rosette of wedge-shaped, untoothed leaves. Leaves are simple, opposite and oval to oblong in shape. Individual flowers have five to seven petals, and are attached close to the stem. This shade-tolerant annual is a native of Asia, but has recently spread into New York and Connecticut. It has hollow stems similar to bamboo, with swollen joints along the stem.
Leaves are broadly egg-shaped, with pointed tips and squarish bases.
It has alternate, glossy leaves that are oval or elliptical. They are smooth or slightly hairy, thin and from one to three inches long. These stems are generously studded with stiff thorns. Leaves are usually made up of seven or nine leaflets, each sharply toothed. Stem leaves are alternate, toothed, and triangular or deltoid.