Hymenasplenium excisum

Aspleniaceae

Hymenasplenium excisum (C.Presl) S.Linds.

Link to Australian Plant Name Index for publication details and synonyms: https://id.biodiversity.org.au/name/apni/51251680

Lithophytic or epiphytic ferns with semi-erect fronds. Rhizome short [to long]-creeping, scaly. Stipe and rachis dark red-brown, sparsely scaly, glossy; stipe 8–25 cm long, 0.5–2 mm diam. Lamina narrowly triangular to ovate or triangular, pinnate with a long-acuminate apex, 15–35 cm long, 5–20 cm wide, pale green, thin, ±glabrous. Pinnae in 10–25 pairs, ±oblong, slightly falcate, inserted at ±right angles to rachis; basal basiscopic portion excised so that each pinna appears to be joined to a short stalk in the lower corner; line of excision at c. 40–50° to midrib; margins serrate; apices acute to acuminate; longest pinnae at or near base, 2.5–9 cm long, 8–15 mm wide, gradually decreasing upwards but abruptly contracted to a ±linear, pinnatifid, apical segment; lower ones deflexed. Sori to 5 mm long, slightly curved. Spores dark with fimbriate or serrate wings and tuberculate or ribbed lacunae; exospores 34.2–34.7 × 23.5–24.9 µm (means). 

Restricted to a small area of the eastern Atherton Tableland in NE QLD. Usually very localised.  Also in Asia, Malesia, and Pacific Islands.

Terrestrial, lithophytic or epiphytic on tree bases near creeks and waterfalls in dark shaded gullies in high rainfall rainforest.

An attractive ornamental fern.

Requires very humid shaded montane tropical conditions which are difficult to replicate in cultivation.

Hymenasplenium unilaterale and Hymenasplenium wildii.

1a.  Pinnae 5–8 pairs, pinnae < than 2.5 cm long, lowland habitat = Hymenasplenium wildii

1b.  Pinnae 9 or more pairs, pinnae > 2.5 cm long, montane habitat = 2.

2a.  Frond apex attenuate, basal pair of pinnae deflexed, lateral pinnae deeply excised = Hymenasplenium excisum

2b. Frond apex not attenuate, basal pair of pinnae not deflexed, lateral pinnae not deeply excised = Hymenasplenium unilaterale