Family, Loosestrife. The flowers of Lythrum are dimorphous, that is, have stamens and pistils of different lengths, so that self-pollination is prevented. This is a large and bushy plant, with slender stems, small leaves, and single (lowers in the upper axils. Petals, 5 to 7. Calyx, tubular, 5 to 7-toothed, with little processes between the teeth. Stamens joined to the calyx, as many or twice as many as petals. Leaves, linear, opposite, sessile, one-ribbed. Summer.