Abrodictyum - Hymenophyllaceae

Abrodictyum rigidum (Sw.) Ebihara & Dubuisson

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Mozambique

Photo: P. Ballings
Mozambique

Photo: P. Ballings
Mozambique

 

 

 

 

Synonyms

Trichomanes rigidum Sw.
Cephalomanes rigidum (Sw.) K.Iwats.
Selenodesmium rigidum (Sw.) Copel.

Common name

Description

Rhizome shortly creeping to suberect, c. 3 mm in diameter; rhizome scales covered with dark brown hairs. Fronds tufted, erect to pendant, dark green. Stipe up to 22 cm long, brown, narrowly winged near apex, glabrous or with sparse brown hairs to 1.5 mm long. Lamina 4-24 × 2-14 cm, 3-4 pinnatifid, narrowly ovate to lanceolate in outline, membranous but tough and leathery. Pinnae 14-20 on each side, shortly stalked, to 7 x 3 cm, uniformly developed; pinnules to 13 on each side, to 1.7 x 0.5 cm; ultimate lobes narrowly linear, to 0.3 mm wide, attenuate, glabrous on both surfaces. Rhachis narrowly winged in the upper part of the lamina. Sori c. 1.5 × 0.7 mm, narrowly conical, borne near the costules of the pinnules on the acroscopic side, not winged; indusium narrowly conical, 0.7-1.5 mm long, 0.5-0.7 mm in diameter, not winged, mouth dilated to 0.9 mm, valves entire; receptacles long, persistent, extruding beyond the sori valves.

Notes

A. rigidum has a stiff, upright habit and finely divided fronds, this makes it easy to distinguish from other Hymenophyllaceae.

Derivation

rigidum: rigid, stiff; the fronds of this species are erect and tough

Habitat

Lithophytic in deeply shaded, continually moist boulders and earth-banks in evergreen forest, along streams and in the spray of or close to waterfalls and rapids. Always in very dark and continually wet areas.

Distribution worldwide

Tropical and Southern Africa, also known from the Indian Ocean islands, South and Central America and the West Indies.

Distribution in Africa

Angola, Burundi, Cameroon, Central African Republic, Congo, Democratic Republic of Congo, Equatorial Guinea (incl. Bioko), Gabon, Ghana, Guinea, Ivory Coast, Kenya, Liberia, Malawi, Mozambique, Nigeria, Rwanda, Swaziland, Tanzania , Zambia, Zimbabwe.

Growth form

Lithophytic, terrestrial.

Literature

  • Beentje, H.J. (2008) Hymenophyllaceae. Flora of Tropical East Africa, Pages 30 - 31. (Includes a picture).
  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Pages 90 - 92. (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 148 - 149. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 190 - 191. (Includes a picture).
  • Kornas, J. (1979) Distribution and ecology of the Pteridophytes in Zambia. Polska Akademia Nauk Wydzial II Nauk Biologicznych. Pages 73 - 74.
  • 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 38.
  • Roux, J.P. (2001) Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report, 13 Page 48. (Includes a picture).
  • Schelpe, E.A.C.L.E. (1970) Pteridophyta. Flora Zambesiaca, 0 Page 78. (Includes a picture).
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