Asplenium dielmannii (no common name) is a medium-sized fern in the spleenwort family (Aspleniaceae) with short, creeping, non-branching rhizomes, and two to five fronds. The erect fronds are 10 to 75 cm (cm) (4 to 30 in) by 5 to 20 cm (2 to 8 in). The stipes (fronds) and rachises (midribs) are purplish black, shiny, and scaly at the base. The blades are 2- to 5-pinnate, herbaceous, lanceolate, and finely dissected. The lanceolate pinnae (divisions or leaflets) have 15 to 35 pairs and are up to 20 cm (8 in) long. Ultimate segments are usually narrow, linear, or linear to lanceolate, and 0.2 to 2 mm (0.01 to 0.1 in). Veins are free, usually with one in each segment. Sori (groups of spores) are marginal, less than 1 mm (0.04 in) long, opening outward on wider segment tips. Indusia (a protective membrane over the sori) are thin. Active growth occurs during the rainy season, from November to May. Frond longevity is up to 18 months, and the number of fronds is dependent on habitat conditions.