Azolla - Salviniaceae

Azolla nilotica Decne. ex Mett.

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Zimbabwe

 

 

 

 

Synonyms

Common name

Description

Rhizome horizontal, branched with the secondary branches alternately pinnately arranged, up to 2 mm in diameter, up to 32 cm long, hairy, with numerous hairy roots in fascicles from the nodes. Leaves 2-lobed; upper lobe broadly ovate to elliptic in outline, apex rounded to broadly pointed, margins forming a broad translucent wing, up to 2 mm long, green, papillate in the centre; lower lobe smaller and thin, colourless. Plant heterosporous; sporocarps in the leaf axils, only on the older parts of the plant.

Notes

A. nilotica has a thick cluster of roots at the nodes, whereas A. pinnata and A. filiculoides have a single, or 2 or 3 roots from the nodes.

Derivation

nilotica: from the valley of the Nile, this fern was first collected on the Nile.

Habitat

Wet mud and shallow water in stagnant or sluggish streams, river backwaters, lake edges, temporary pools, apparently intolerant of shade and not in forest pools.

Distribution worldwide

See African distribution.

Distribution in Africa

Burundi, Dem. Republic of Congo, Ethiopia, Gabon, Kenya, Malawi, Mozambique, Somalia, Sudan and South Sudan, Tanzania , Zambia, Zimbabwe.

Growth form

Aquatic.

Literature

  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Pages 82 - 83. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 493 - 494. (Includes a picture).
  • Kornas, J. (1979) Distribution and ecology of the Pteridophytes in Zambia. Polska Akademia Nauk Wydzial II Nauk Biologicznych. Pages 122 - 123.
  • Roux, J.P. (2009) Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands. Strelitzia 23, South African National Biodiversity Institute, Pretoria. Pages 58 - 59.
  • Roux, J.P. (2001) Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report, 13 Page 179.
  • Schelpe, E.A.C.L.E. (1970) Pteridophyta. Flora Zambesiaca, 0 Pages 70 - 71. (Includes a picture).
  • Verdcourt, B. (1999) Azollaceae. Flora of Tropical East Africa, Pages 2 - 4. (Includes a picture).
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