It forms upright and vigorous clumps, reaching 50 to 80 cm in height, developing by rhizomes into gradually expanding colonies. The stems are robust, slightly hairy, bearing lanceolate to oval leaves, opposite or whorled in threes, of a medium matte green, slightly pubescent to the touch.
The flowers are a deep golden yellow, star-shaped, gathered in dense whorls at the axils of the upper leaves along the entire length of the stems, creating a very characteristic luminous chandelier effect. In its natural habitat, its flowering extends from June to August. In cultivation, it generally blooms from June to July.
Its ability to quickly colonize through its underground rhizomes should be considered before any planting; it is better suited to large naturalized areas or banks than to contained flower beds. It is cultivated in fresh to moist, rich soil, in sun or partial shade, without particular difficulty and with total hardiness.