Parablechnum montanum

Detailed description

Rhizome short creeping; scales to 12 × 3 mm, linear to lanceolate, acuminate, light reddish brown, sometimes tending to be slightly bicolorous with a somewhat darker central region, entire to finely toothed. Fronds dimorphic, erect, 100–600 × 30–250 mm, widest at or below the middle of the lamina; sterile and fertile fronds similar in length. Stipes 70–450 mm (stipes of fertile fronds often longer than stipes of sterile fronds), slender, usually less than c. 3 mm diameter, pale brown or pinkish brown, darkening at base, sometimes darker and blotchy (especially fertile fronds); stipes scaly; scales variable in size, 2–8 × 5–20 mm, but mostly small, appressed, linear, ovate or cordate, pale brown, brown, reddish brown, or “black spot”, entire or toothed, sometimes branched at base. Lamina ovate to narrowly deltoid, mid or dark olive green and shiny at maturity, 1-pinnate, 3–20 pairs pinnae. Rachis and costae pale pinkish brown, brown, or reddish brown (often paler for sterile fronds); with moderately dense scales and irregular branched hairs; scales 1–10 × 5–10 mm, mostly inconspicuous, linear, branched or stellate, sometimes appressed; peltate “black spot” scales (especially conspicuous on costae) usually 2–3 × c. 1 mm, broadly lanceolate-ovate, with attenuate apices (twisted in dried specimens) and irregular marginal outgrowths, intermixed with pale linear (to 6 mm) and smaller pale dendritic scales. Sterile pinnae 25–140 × 10–20 mm, oblong to lanceolate, often falcate, apices acute to attenuate, usually acuminate and becoming increasingly acute towards the base of the lamina, truncate or rounded-cordate at rachis; shortly petiolate or sub-petiolate at base of lamina becoming basiscopically adnate and decurrent at apex; coriaceous; margins toothed and often markedly crenate; veins simple or once-furcate; small branched or stellate scales often extending on to surface of pinnae; basal pinnae as long as or slightly shorter than middle pinnae, rarely less than half their length, more deflexed, and with more obtuse to rounded apices, auricles and auriculate pinnae bases absent; terminal pinna more elongate. Fertile pinnae 40.0–160.0 × 2.5–5.0 mm, narrow, linear, acuminate, sessile or shortly petiolate at base of lamina, becoming basiscopically adnate and winged towards apex; sori covering underside other than apex; indusium brown, laciniate. Spores 42–60 × 23–46 µm.