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.
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.
nilotica: from the valley of the Nile, this fern was first collected on the Nile.
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.
See African distribution.
Distribution in Africa
Burundi, Dem. Republic of Congo, Ethiopia, Gabon, Kenya, Malawi, Mozambique, Somalia, Sudan and South Sudan, Tanzania , Zambia, Zimbabwe.
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.
Lawalree, A. (1976) Azollaceae.Flore d' Afrique Centrale, Page 4.
Roux, J.P. (2001) Conspectus of Southern African Pteridophyta.Southern African Botanical Diversity Network Report, 13 Page 179.
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.
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).