Isoetes - Isoetaceae

Isoetes schweinfurthii A. Braun ex Baker

 

 

 

 

Synonyms

Calamaria schweinfurthii A. Braun ex Baker
Isoetes rhodesiana Alston
Isoetes kersii Wanntorp

Common name

Description

Pseudo-corms 3-lobed; bud scales dark brown to blackish, triangular-cuspidate, ± 6 × 4 mm. Leaves 5-40, narrow, stiff, 150-600 × c.1 mm (at apex) - c.10 mm (around sporangium), broadly winged, apex tapering to a point. Ligule narrowly triangular, sides convex, abruptly pointed, 2-6 mm long, pale, covered by a membranous serrate lip in the lower half. Velum absent or reduced to a vestigial rim. Sporangia 4-12 × 5-9 mm, oblong-obovate to circular. Megaspores 0.4-0.5 mm in diameter, ash-grey to whitish, upper surface almost smooth or with a few tubercles, lower tuberculate with conical warts. Microspores not seen.

Notes

I. alstonii is distinguished from I. schweinfurthii by its 2-lobed pseudo-corm. I. schweinfurhii is separated from I. aequinoctialis by lacking a velum.

Derivation

schweinfurthii: named after Dr Georg August Schweinfurth (1836-1925), German botanical collector and taxonomist.

Habitat

Shallow seasonally inundated pans in dry deciduous woodland or sometimes in sandy soils overlying sheetrock along river margins.

Distribution worldwide

Africa, Madagascar.

Distribution in Africa

Angola, Burkina Fasso, Central African Republic, Ethiopia, Ivory Coast, Kenya, Malawi, Morocco and Western Sahara, Mozambique, Namibia, Senegal, South Africa, Sudan and South Sudan, Tanzania , Zambia, Zimbabwe.

Growth form

Terrestrial.

Literature

  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Page 36. (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 70 - 71. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 153 - 154. (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. Page 10.
  • Roux, J.P. (2001) Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report, 13 Pages 29 - 30.
  • Schelpe, E.A.C.L.E. (1970) Pteridophyta. Flora Zambesiaca, 0 Page 30. As Isoetes rhodesiana
  • Verdcourt, B. (2005) Isoetaceae. Flora of Tropical East Africa, Pages 4 - 6.
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