Asplenium - Aspleniaceae

Asplenium unilaterale Lam.

Photo: P. Ballings
Zimbabwe

Photo: P. Ballings
Zimbabwe

 

 

 

 

Synonyms

Asplenium resectum Sm.
Hymenasplenium unilaterale (Lam.) Hayata
Asplenium unilaterale Lam. var. majus (C.Chr.) Sledge

Common name

Description

Rhizome creeping, c.3 mm thick; rhizome scales 2-3 mm long, dark brown, lanceolate, margins entire. Fronds spaced apart, erect, herbaceous. Stipe 7.5-22 cm long, stipe and rhachis glabrous, dark brown to almost black. Lamina 17-30 × 5-10 cm, pinnate, narrowly elliptic to oblong in outline, lowest pinnae hardly reduced but often more lobed, apex decrescent and tapering to a point. Pinnae 12-20 pairs, glabrous, narrowly triangular-rhombic or shaped like a parallelogram, up to 3.5-6 x 0.5-1.2 cm, upper margin toothed to lobed, costa forming the lower margin for about 1/2 to 3/4 of the pinna length. Sori 2-10(-14), oval-linear, set along the veins towards the apex of the pinnae, 2.5-3 mm long; indusium narrowly oblong, membranous, entire, 0.8 mm wide.

Notes

This taxa is easily recognisable by the costa forming the lower edge of the pinna for 1/2 to 3/4 of its length. and differs from A. obscurum by having a dark brown to almost black stipe and smaller sori (± 3 mm long) that are sparsely scattered towards the pinna apex.

Derivation

unilaterale: one-sided, referring to the form of the pinnae.

Habitat

Moist evergreen or riverine forest, deeply shaded stream banks or near waterfalls.

Distribution worldwide

Africa, Mascarene Isl., Pacific Isl., S and E Asia.

Distribution in Africa

Angola, Cameroon, Central African Republic, Congo, Equatorial Guinea (incl. Bioko), Ethiopia, Ghana, Guinea, Ivory Coast, Kenya, Liberia, Malawi, Niger, Nigeria, Sierra Leone, Sudan and South Sudan, Swaziland, Tanzania , Uganda, Zimbabwe.

Growth form

Lithophytic, terrestrial.

Literature

  • Beentje, H.J. (2008) Aspleniaceae. Flora of Tropical East Africa, Pages 28 - 29. (Includes a picture).
  • Burrows, J.E. (1990) Southern African Ferns and Fern Allies. Frandsen, Sandton. Page 222. (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 600 - 601. (Includes a picture).
  • Jacobsen, W.B.G. (1983) The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 340 - 341. (Includes a picture).
  • Roux, J.P. (2001) Conspectus of Southern African Pteridophyta. Southern African Botanical Diversity Network Report, 13 Page 172. (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 99 - 100.
  • Schelpe, E.A.C.L.E. (1970) Pteridophyta. Flora Zambesiaca, 0 Page 174.
  •