Cabombaceae
The Cabombaceae are a family of aquatic, herbaceous flowering plants. A common name for its species is water shield. The family is recognised as distinct in the Angiosperm Phylogeny Group IV system. The family consists of two genera of aquatic plants, Brasenia and Cabomba, totalling six species.
Description
Vegetative characteristics
Cabombaceae are perennial, rhizomatous, aquatic herbs with slender, branched rhizomes and adventitious roots. The leaves are whorled, alternate, or opposite. Both floating and submerged leaves are produced.Generative characteristics
The solitary, pedunculate, bisexual, chasmogamous, actinomorphic, inodorous flowers float on the water surface or extend beyond it. The gynoecium consists of 2–18 free carpels. The indehiscent, follicle-like or achene-like fruit bears 1–3 seeds.Distribution
The Cabombaceae are all aquatic, living in still or slow-moving waters of temperate and tropical North and South America, Europe, Asia, Africa, and Australia. Although found on all continents but Antarctica, the plants tend to grow in relatively restricted ranges.Fossil record
The family has an extensive fossil record from the Cretaceous with plants that exhibit affinities to either the Cabombaceae or Nymphaeaceae occurring in the Early Cretaceous.One such likely Cretaceous member is the genus Pluricarpellatia, found in rocks 115 million years old in what is now Brazil. Scutifolium jordanicum David W.Taylor, G.J.Brenner et S.H.Basha has been described from the Lower Cretaceous of Jordan. Garasbahia flexuosa Krassilov et Bachia has been described from the mid-Cretaceous of Morocco.