Isoetes - Isoetaceae

Isoetes wormaldii Sim

Photo: JE. Burrows
South Africa

Photo: JE. Burrows
South Africa






Common name


Pseudo-corm 3-lobed; bud scales absent. Leaves 30-70, flaccid, floating when mature, oval to flattened in transverse section, terminating abruptly in a rounded apex, 150-470 x 2-3 mm, base flaring to a 3 mm wide wing on either side of sporangia. Ligule narrowly triangular, 2.5-3.0 mm long, dark brown. Velum absent or very narrow, up to 1 mm wide. Sporangia ovate-triangular, 2.0-2.5 x 3.0-4.5 mm. Megaspores ± 0.6 mm in diameter, white, reticulate, the reticulations enclosing deep cavities with raised 'knobs' present at many of the junctions of the reticulations, proximal surface similar to the distal surface.



wormaldii: this species was first found by Mr. W.H. Wormald in Queen's Park, East London in 1893.


Temporary pools and streams or as a perennially submerged in slow-flowing rivers, rooting in mud below water level.

Distribution worldwide

See African distribution.

Distribution in Africa

South Africa.

Growth form



  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Page 33. (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 74 - 75. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 152 - 153. (Includes a picture).
  • 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 11 - 12.