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The families of flowering plants

L. Watson and M.J. Dallwitz

Cabombaceae A. Rich.

~ Nymphaeaceae.

Including Hydropeltideae (Hydropeltidaceae) Dum.

Habit and leaf form. Aquatic herbs; laticiferous, or non-laticiferous. Perennial; rhizomatous. Hydrophytic; rooted. Leaves submerged, or submerged and floating. Not heterophyllous (Brasenia), or heterophyllous (Cabomba). Leaves alternate, or alternate and opposite; spiral, or distichous, or four-ranked; non-sheathing; not gland-dotted; simple, or simple and compound; peltate (in Brasenia), or not peltate; epulvinate. Lamina dissected (submerged leaves), or entire (floating leaves); when dissected, finely dichotomously dissected; often cordate. Leaves exstipulate.

Leaf anatomy. Stomata presumably present (?); anomocytic (?). The mesophyll containing mucilage cells, or not containing mucilage cells; without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (Cabomba).

Axial (stem, wood) anatomy. Secretory cavities present (articulated); with latex. Cork cambium absent. Primary vascular tissues in the axis consisting of scattered bundles (these closed, monocot-like, but the rhizomes described as having “double bundles”). Secondary thickening absent. The axial xylem without vessels.

The axial xylem with tracheids (with spiral or annular thickenings).

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; 3 merous; cyclic, or partially acyclic. When acyclic the gynoecium acyclic, or the androecium acyclic and the gynoecium acyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla (but the calyx petaloid); 6; 2 whorled; isomerous. Calyx 3 (petaloid); 1 whorled; polysepalous; regular. Corolla 3; 1 whorled; polypetalous; regular; yellow, or purple, or white. Petals clawed, or sessile.

Androecium 3–6 (Cabomba), or 12–18 (Brasenia). Androecial members when many, maturing centripetally; free of the perianth; all equal; free of one another. Androecium exclusively of fertile stamens. Stamens 3–6, or 12–18; isomerous with the perianth to diplostemonous, or polystemonous; filantherous (with the filaments somewhat flattened). Anthers dehiscing via longitudinal slits; extrorse; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate (sometimes trichotomosulcate).

Gynoecium (2–)3–18 carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth, or increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous; superior. Carpel non-stylate, or stylate (stigma then subsessile); with a longitudinal stigmatic surface (Brasenia), or apically stigmatic (Cabomba); (1–)2 ovuled, or 3 ovuled. Placentation marginal. Ovules pendulous; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Endosperm formation helobial. Endosperm haustoria present; chalazal.

Fruit non-fleshy; an aggregate. The fruiting carpel indehiscent; a follicle. Seeds endospermic. Perisperm present. Cotyledons 2.

Physiology, phytochemistry. Not cyanogenic. Alkaloids present. Saponins/sapogenins absent. Sieve-tube plastids S-type.

Geography, cytology. Holarctic, Paleotropical, Neotropical, and Australian. Temperate to tropical. The monotypic Brasenia schreberi in tropical America, Africa, India and E. Australia, with Cabomba native to warm America but distributed worldwide via discarded aquarium plants.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Nymphaeiflorae; Nymphaeales. Cronquist’s Subclass Magnoliidae; Nymphaeales. APG 3 peripheral angiosperms; Superorder Nymphaeanae; Order Nymphaeales.

Species 8. Genera 2; Brasenia (B. schreberi), Cabomba (7 spp.).

General remarks. The Metcalfe and Chalk (1965) account of Nymphaeaceae sensu lato employed here does not permit satisfactory anatomical treatment of this sensu stricto family.

Economic uses, etc. Cabomba caroliniana is a declared noxious weed in nutrient rich shallow waters in North America and where introduced in Australia and Europe, clogging channels and drains and seriously restricting water flow and recreational activites.

Illustrations. • Cabomba furcata, as C. piauhiensis: Hook. Ic. Pl. 7–8 (1844). • Technical details: Cabomba. • Mucilage hairs of Cabomba aquatica and Brasenia peltata, with hairs of Nymphaeaceae. Solereder, 1908.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 13th March 2017.’.