Butomus umbellatus, the so-called Flowering Rush, the only species of the genus, and one of the most beautiful English water-plants. It often grows in deep water, having a starchy rhizome, which is roasted and eaten in some parts of Asia. Its leaves are narrow, three-edged, filled with large air spaces, and several feet long, but are overtopped by the stout cylindric peduncle which bears an umbel. The flowers are an inch across, with a rosy perianth of six leaves, nine stamens, and six carpels. The stamens are hypogynous, six being due to the collateral chorisis of three outer ones. The fruit is a ring of six follicles.