Plants growing on soil and rock, occasionally in water, 10–30 mm tall, yellow-green to dark green, brown or blackened below, densely gregarious. Stems simple or occasionally branched; in section with a strong central strand of small thin-walled cells. Leaves in numerous pairs, crowded, imbricate at the base, patent, falcate when moist, oblong-lingulate, 2–3 mm long, strongly coiled when dry; apex obtuse to rounded; margins serrulate on the dorsal and apical laminae, irregularly so near the apex. Vaginant laminae c. 3/4 leaf length, open or nearly so, rounded above, joining at or near the costa; margins crenulate to weakly serrulate; dorsal lamina tapering at the base, mostly ending above the insertion. Lamina cells of the dorsal and apical laminae irregularly rounded hexagonal, mostly 7–15 µm wide, mammillose. Costa of oblongifolius-type, ending 5–12 cells below the apex.

Dioicous. Perigonia terminal on stems. Perichaetia terminal on stems. Perichaetial leaves longer than vegetative leaves, with acute apices. Setae terminal, to 5 mm long, yellow to orange-brown, stout, arcuate. Capsules inclined, asymmetrical, oblong, 1.0–1.5 mm long. Operculum rostrate, often oblique, ±equal in length to capsule. Calyptra smooth, cucullate. Peristome teeth of fasciculatus-type; basal part with low trabeculae on the outer face and with low vertical smooth or papillose ridges, continuing into the bases of forks; forks distally coarsely papillose. Spores 14–16 µm diameter.

Beever et al. (2002) state that the rounded apex of the vaginant lamina is a useful diagnostic character. Fissidens asplenioides can be confused with F. oblongifolius; however, the margins of the vaginant laminae of F. asplenioides are entire and the cells are longer than wide, while in F. oblongifolius the margins are crenulate by projecting cell ends, and the cells are oblong-ovate.

Native.

A common species on soil and rock in a wide range of habitats, in more exposed sites the plants are more yellowish.

Fissidens asplenioides Hedw., Sp. Musc. Frond. 156 (1801). Type: Jamaica, O.Swartz; holo: G n.v.; iso: NY n.v.

Taxonomic synonyms

Fissidens ligulatus Hook.f. & Wilson, Fl. Nov.-Zel. 2: 63 (1854); Conomitrium ligulatum (Hook.f. & Wilson) Hampe, Fragm. 11 (Suppl.): 52 (1881). Type: Bay of Islands, New Zealand, Colenso 215; lecto: BM, fide Bruggeman-Nannenga et al., J. Hattori Bot. Lab. 77: 259 (1994); isolecto: BM.

W.A.: Chiddarcooping Hill, 43 km N of Wistonia, R.Wyatt & A.Stoneburner 4069 (PERTH).

S.A.: Upper Sturt, Mount Lofty Range, D.G.Catcheside 53-255 (AD).

Qld: Eungella Natl Park, I.G.Stone 12360 (MEL).

N.S.W.: Brown Mtn, near Nimmitabel, D.G.Catcheside 65-341 (AD).

A.C.T.: Tidbinbilla Valley, D.G.Catcheside 65-55 (AD).

Vic.: near Eurobin Falls, Mt Buffalo, D.G.Catcheside 69-223 (AD).

Tas.: Dip Falls, S of Stanley, I.G.Stone 25254 (MEL).

The taxonomic placement of F. asplenioides in the subgeneric classification remains unresolved. It has traditionally been placed in section Amblyothallia Müll.Hal. (e.g. Brotherus, 1924; Bruggeman-Nannenga & Berendsen, 1990; Pursell & Bruggeman-Nannenga, 2004; Pursell, 2007) or in section Serridium Müll.Hal. (Allen, 1980). The peristome is unusual in that the filaments are flat and scarcely twisted and papillose distally. This structure was named fasciculatus-type by Bruggeman-Nannenga & Berendsen (1990), a structural type also found in the Dicranaceae. In section, the costa of F. asplenioides is also deviant in that the epidermal cells have larger lumena than the stereid cells, making this a modified oblongifolius-type structure. Suzuki & Iwatsuki (2007) established the subgenus Neoamblyothallia Tad.Suzuki & Z.Iwats. for the other members of section Amblyothallia. 

G.A.M.Scott & I.G.Stone, The Mosses of Southern Australia 85, pl. 7; 87, pl. 8; 89, pl. 9 (1976); J.Beever, B.Malcolm & N.Malcolm, The Moss Genus Fissidens in New Zealand : an illustrated key 16 (2002); H.Streimann, The Mosses of Norfolk Island 75, fig. 31 (2002); D.Meagher & B.Fuhrer, A Field Guide to the Mosses and Allied Plants of Southern Australia 39 (2003).

Beever, J.E., Malcolm, W. & Malcolm, N. (2002). The Moss Genus Fissidens in New Zealand – an illustrated key. (Micro-Optics Press, Nelson).

Brotherus, V.F. (1924). Fissidentaceae, in H.G.A.Engler & K.A.E.Prantl, Nat. Pflanzenfam. 2nd edn, 10: 143–­155.

Bruggeman-Nannenga, M.A. & Berendsen, W. (1990). On the peristome types found in the Fissidentaceae and their importance for the classification. J. Hattori Bot. Lab. 68: 193–234.

Pursell, R.A. (2007). Fissidentaceae, Flora Neotropica Monograph 101. (Botanical Gardens Press, New York).

Pursell, R.A. Bruggerman-Nannenga, M.A. (2004). A Revision of the Infrageneric Taxa of Fissidens. The Bryologist 107: 1-20.

Seppelt, R.D. & Stone, I.G. (2016). Australian Mosses Online 70. Fissidentaceae. Australian Biological Resources Study, Canberra. Version 16 June 2016. http://www.anbg.gov.au/abrs/Mosses_online/70_V2_Fissidentaceae.html

For more details about the history of this treatment see Fissidentaceae profile.