Dryopteris - Dryopteridaceae

Dryopteris ruwenzoriensis C.Chr. ex Fraser-Jenk.

 

 

 

 

Synonyms

Common name

Description

Rhizome short, decumbent to suberect, to 15 mm in diameter, set with roots, crowded persistent stipe bases, and scales; rhizome scales dull, chestnut to rust coloured, papery, broadly attached, narrowly ovate to lanceolate, to 12 x 4 mm, broadly cuneate, margin wavy to irregular. Fronds tufted, erect to arching, to 1.35 m long. Stipe chestnut coloured at the base, straw coloured higher up, to 72 cm long, variously set with hairs and minute, membranous scales. Lamina firmly herbaceous, ovate to triangular in outline, to 64 x 54 cm, 2-pinnate-pinnatifid to 3-pinnate, with up to 5 pinna pairs. Pinnae petiolate, the petiole to 6 mm long, near opposite to alternate, more widely spaced near the base, slightly imbricate or not, the basal pair conspicuously basiscopically developed, inaequilaterally narrowly ovate to triangular in outline, 1-pinnate-pinnatifid to 2-pinnate, the basal pair the longest, to 31 x 12.5 cm wide, with up to 2 pinnule pair. Pinnules petiolate, the petiole to 2 mm long, sessile and progressively more broadly attached and basiscopically decurrent towards the apex, lanceolate to oblong-acuminate, pinnatifid to deeply lobed, the acroscopic pinnule on the basal pinna to 5.1 x 2 cm, the basiscopic pinnule on the basal pinna to 8.8 x 2.6 cm, near opposite to alternate, spaced to slightly imbricate. Ultimate segments closely spaced but not imbricate, oblong-obtuse to oblong-truncate, to 1.6 x 0.9 cm, shallowly and inconspicuously lobed; lobes with conspicuously and acutely toothed apices, upper surface hairless or with a few hairs and hair-like scales along the costules, lower surface variously set with scales and minute hairs along the veins. Venation pinnately branched in the segments, the vein branches pinnately branched, forked, or simple near the apex, evident, ending in the teeth near the margin. Rhachis, pinnae rhachis straw coloured, upper surface shallowly grooved, becoming narrowly winged near the apex, initially variously set with hairs and minute scales. Costae upper surface shallowly grooved, pronounced lower surface, narrowly winged along the entire length, variously scaled. Sori circular, to 1.5 mm in diameter at maturity, medial to inframedial, predominantly on the vein branches, discrete, essentially in 2 rows on the segments; exindusiate.

Notes

Derivation

ruwenzoriensis: refering to the Ruwenzori Mountains on the border between the DRC and Uganda, the type locality of this species.

Habitat

Confined to mountainous regions, at lower elevations the species is confined to moist evergreen forests, but at higher elevations it occupies bamboo forests and the ericaceous belt.

Distribution worldwide

See African distribution.

Distribution in Africa

Dem. Republic of Congo, Rwanda, Uganda.

Growth form

Lithophytic, terrestrial.

Literature

  • 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 123 - 124.
  • Roux, J.P. (2012) A revision of the fern genus Dryopteris (Dryopteridaceae) in sub-Saharan Africa. Phytotaxa, 70(1) Pages 96 - 97. (Includes a picture).
  • Roux, J.P.; Shaffer-Fehre, M. & Verdcourt, B. (2007) Dryopteridaceae. Flora of Tropical East Africa, Page 46. (Includes a picture).
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