Brasenia Schreb.

Slender, perennial herbs; rhizomes small, erect with submerged and floating leaves and floating shoots; submerged parts covered by mucilaginous jelly. Leaves mostly crowded near the summit, long-petioled;juvenile leaves subulate to eccentrically peltate, submerged; adult leaves centrally peltate, floating. Flowers reddish, inconspicuous, on peduncles of unequal length, emerged above water at anthesis. Sepals (2-)3(-4), somewhat petaloid. Petals (2-)3(-4). Stamens (12-)18 - 36, with or without short apiculate sterile appendages; thecae (microsporangia) lateral; pollen 1-sulcate. Carpels (4-)7 - 18, each with (1-)2(-4) pendulous ovules in laminar or dorsal position. Ovules atropous, anatropous at maturity. Pods coriaceous, 1 - 4-seeded.

Sporadically distributed in all the continents, except Europe; but seeds reported from pleistocene and interglacial deposits in Europe; monotypic.

Notes. The floating shoots bear floating leaves and flowers at nodes which are the products of axillary buds of runners. Though it appears as a continuous axis, it represents a sympodial branch system (Richardson in Univ. Calif. Publ. Bot. 47: 4. 1969). In gregarious populations, the floting shoots form a dense interwoven mass.

List of Lower Taxa