Neotropical Ruppiaceae

Anna Haigh

Royal Botanic Gardens, Kew, UK. 

Description

Habit: aquatic herbs, submersed, mostly annual (occasionally surviving winter as underground rhizome). Leaves alternate, simple, sessile, sheathed at base, the sheaths fused for entire length; ligule absent; blades linear, the margins entire, except at apex, the apex irregularly serrate; venation of midrib only. Inflorescences terminal, 1- few-flowered spikes, the spikes first enclosed by 2 sub-opposite foliage leaves; peduncle varying in length (by species), projecting inflorescence to water surface (where pollination occurs). Flowers actinomorphic, bisexual; perianth absent; androecium of 2 sessile stamens, the anthers dehiscing by longitudinal slits, each bearing a broad connective with a dorsiventral outgrowth; gynoecium apocarpous, the ovaries superior, the carpels (2-)4(-16), stalked, the stigma sessile or nearly so; placentation marginal distally, the ovule 1 per carpel, ± pendulous near apex of carpel. Fruits drupes, nearly spherical, stalked, the endocarp rigid; seeds 1 per fruit, the seed coat permanently attached to endocarp.

Notes on delimitation

  • Placed in the Alismatales, its closest relative is Cymodoceaceae.

Distribution in the Neotropics

  • A subcosmopolitan family of 1 genus (Ruppia L.) and 1-12 species depending on taxonomic framework, with about 1-7 species native to fresh and brackish waters of coastal as well as inland Neotropics.

Distinguishing characters (always present)

Status

  • Native.

General notes

  • Ruppiaceae are useful in stabilizing substrates and removing suspended particles from the water column.

Important literature

Haynes, R.R., 2004. Ruppiaceae. Pp. 479-480. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.

Haynes, R.R., Holm-Nielsen,L.B. and Les,D.H. 1998. Ruppiaceae. In: K. Kubitzki (ed.), The families and genera of vascular plants 4: 445-448. Springer Verlag, Berlin.

Novelo, R.A., 1991. Ruppia didymia (Potamogetonaceae) en México y las Antillas. An. Inst. Biol. Univ. Nac. Auton. Méx. Ser. Bot. 62:173-180.

How to cite

Haigh, A. (2009). Neotropical Ruppiaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Ruppiaceae.htm.