Neotropical Menyanthaceae

Jon L.R. Every

University of Plymouth, U.K. 

Description

Aquatic perennial herbs. Leaves above the water-level, surfacing or rarely submerged, alternate, simple, entire, orbicular, occasionally slightly succulent, cordate or reniform, margins entire, dentate or crenate with hydathodal glands, venation palmate; estipulate; petiolate, petiole bases sheathing. Flowers in terminal or axillary fascicles, heads, panicles or solitary, bisexual or occasionally functionally unisexual, actinomorphic; bracts small and inconspicuous; sepals 5, basally connate; petals 5, basally connate, winged; stamens 5, adnate to and alternating with the perianth, staminodes 5 alternating with stamens, anthers dorsifixed, dehiscing via longitudinal slits; ovary superior-partly inferior, unilocular, syncarpous; carpels 2, stigma on style or sessile. Fruit a capsule. Seeds 1-many, dry, 0.4 - 5.2 mm, flattened or lenticular.

Notes on delimitation

  • Placed in the Asterales by the APG (APGIII).

Distribution in the Neotropics

  • Non-marine hydrophytes and helophytes of the Neotropics.
  • Recorded in Brazil, the Caribbean, Central America, Colombia, Ecuador, Mexico, Argentina and Paraguay.

Distinguishing characters (always present)

  • Intercellular air canals in stems.
  • Palmate venation in leaves.
  • Fimbricate petals.

Key differences from similar families

  • The Gentianaceae differs in that their members having opposite leaves.

Number of genera

  • One genus: Nymphoides Ség. with four species, N. fallax Ornduff, N. grayana Kuntze, N. humboldtiana Kuntze (N. indica (L.) Kuntze) and N. flaccida L. B. Sm.

Status

  • Native.

General notes

  • Also known as the Bog-Bean family.

Important literature

Brummitt, R.K. 2007. Menyanthaceae. In: V.H. Heywood, R.K. Brummitt, A. Culham and O. Seberg (eds.). Flowering Plant Families of the World. Pp 212-213. Royal Botanic Gardens, Kew.

Ornduff, R. 2004. Menyanthaceae. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. and Heald, S.V. (eds.). Flowering Plants of the Neotropics. Pp 249-250. The New York Botanical Garden, Princeton University Press, Princeton.

Stevens, P.F. 2008. Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/

Click images to enlarge


Nymphoides indica © Paul Maas.