Perennials, rhizomatous or densely caespitose; leaf blade flat, canaliculate, subterete to terete, uni-, bi- or pluritubular, imperfectly or perfectly septate. Inflorescence reduced to a single flower or a single terminal head, or anthelate of several to many heads; floral bracteoles absent. Tepals often white or whitish, or dark castaneous-brown. Stamens frequently exserted. Capsule unilocular, rarely ±triseptate, not trilocular. Seeds usually with two distinct appendages.