Salvinia - Salviniaceae

Salvinia molesta D.S.Mitch.

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Zimbabwe

 

 

 

 

Synonyms

Salvinia auriculata sensu Schelpe, non Aubl.
Salvinia natans sensu Cadet, non (L.) All.

Common name

Description

Rhizome horizontal, repeatedly dichotomously branched, up to 1.2 mm in diameter, with brown hairs up to 2 mm long on the undersurface. Leaves in whorls of three, two unwettable floating leaves and a submerged leaf at each node; floating leaves broadly obovate to orbicular, apex rounded to notched, base heartshaped, folded along the midrib in vigorous plants, 2.5-2.4-3 cm, upper surface covered with parallel rows of multicellular stalked hairs each subtended by 3-4 arms which re-unite at the apex in a cagelike structure, lower surface only simple hairs near the midrib; submerged leaf finely dissected, rootlike, up to 12 cm long, set with brown hairs up to 2 mm long. Sporocarps in 2 rows along one lobe of the submerged leaf, ovoid, c. 2-3 mm in diameter, resembling a string of beads, heterosporous.

Notes

Derivation

molesta: annoying, troublesome; a reference to the difficulties in eradicating the spreading nature of this plant in aquatic habits such as Lake Kariba along the Zambezi River. The popular name is, therefore, 'Kariba Weed'.

Habitat

In mud and backwaters of lakes, dams and rivers, often forming extensive free-floating mats.

Distribution worldwide

Introduced from tropical America to southern, central and east Africa; also naturalised on Mauritius & Rodrigues Island, India, Sri Lanka, Australia and possibly Malaysia, Indonesia and New Zealand.

Distribution in Africa

Benin, Botswana, Congo, Dem. Republic of Congo, Kenya, Mozambique, Namibia, South Africa, Zambia, Zimbabwe.

Growth form

Aquatic.

Literature

  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Pages 80 - 81. (Includes a picture).
  • Crouch, N.R., Klopper, R.R., Burrows, J.E. & Burrows, S.M. (2011) Ferns of Southern Africa, A comprehensive guide. Struik Nature. Pages 218 - 219. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 490 - 491. (Includes a picture).
  • Kornas, J. (1979) Distribution and ecology of the Pteridophytes in Zambia. Polska Akademia Nauk Wydzial II Nauk Biologicznych. Page 122.
  • Roux, J.P. (2001) Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report, 13 Page 178.
  • Roux, J.P. (2009) Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands. Strelitzia 23, South African National Biodiversity Institute, Pretoria. Page 59.
  • Schelpe, E.A.C.L.E. (1970) Pteridophyta. Flora Zambesiaca, 0 Page 67. As Azolla auriculata (Includes a picture).
  • Verdcourt, B. (2000) Salviniaceae. Flora of Tropical East Africa, Page 3. (Includes a picture).
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