A low, decumbent, much-branched plant of semi-shrubby character, growing about 1 ft high; stems winged. Leaves opposite, 1⁄2 to 1 in. long, narrowly obovate, tapering at the base; stalkless. Flowers terminal, usually solitary or in threes, yellow, 1⁄2 to 3⁄4 in. across; petals four, arranged in the form of a St Andrew's Cross; sepals four, in two pairs of unequal size, the larger ones almost as long as the petals.
Native of eastern United States; introduced in 1759. This species is grown in the rock garden at Kew, where it flowers from July to September; it likes a light, loamy soil, and can be increased by cuttings taken in July. It appears to be a rather delicate plant, or perhaps naturally short-lived, for which reason it is advisable to renew the stock from seed occasionally.