Acrostichum speciosum

Pteridaceae

Acrostichum speciosum Willd.

Link to Australian Plant Name Index for publication details and synonyms: https://id.biodiversity.org.au/name/apni/74408

Mangrove Fern

Terrestrial ferns of moist ground, often on muddy ±saline substrates. Rhizome stout, creeping to erect, with large scales c. 8 mm long and thick fleshy prop roots. Fronds 1–1.5 (–3) m tall. Stipe up to one-third length of frond, scaly at base. Lamina dull green, 1-pinnate (simple in juvenile fronds), stiff, somewhat leathery, glabrous. Pinnae numerous, ascending, narrowly oblong to lanceolate, conspicuously stalked (except perhaps the uppermost ones); upper fertile pinnae smaller; apex narrowed, sometimes with a short abrupt point to c. 5 mm longpinnae smaller and fertile; lower sterile pinnae usually to c. 10 (–15) cm long, 2.5–3.5 cm wide, sometimes larger; apex narrowly acuminate.; lowermost pinnae sometimes reduced; all pinna margins entire. Secondary veins none; tertiary veins forming a close network of oblique (except for the costal ones) elongate-hexagonal meshes without free included veinlets. Sporangia covering lower surface of fertile pinnae, or only in the apical part; paraphyses abundant, filiform, several-celled with dark end-cells. Spores tetrahedral. 

Widespread in the Indo-Pacific. In Australia this species occurs along the coastal fringe of WA, NT and QLD from the Kimberley WA to Southport QLD.

Terrestrial, usually in the supra-littoral zone on the fringes of riparian and swamp mangrove forest, on the fringes of brackish swamp forest, on the border between mangrove and vine forest or adjacent springs or freshwater river systems.

One of few ferns that grow in salt affected areas.

An easy to cultivate fern if placed in bright moist situations in the garden in tropical and subtropical areas. This fern can also be grown in a container in a moisture retentive terrestrial mix. It commonly germinates from spore around the garden, especially in salt affected areas and may be invasive in some situations.

Acrostichum speciosum can be distinguished by having narrower pinnae (< 35 mm wide) and shorter rhizome scales (< 10 mm long) from Acrostichum aureum which has broader pinnae (40–50 mm wide) and longer rhizome scales (c. 40 mm long).