Calyx, 5-toothed, prettily veined, much swollen. Petals, 5, so deeply divided as to seem like 10. Stamens, 10. Styles, 3. Flowers, in loose panicles. Leaves, ovate to lance-shaped, opposite.

A smooth plant, 1 foot high, easily known by its inflated calyx and good-sized flowers. An imported species, now common in some parts of New England and New York, extending westward to Illinois. Dry fields, waste places.