Asplenium chathamense

Detailed description

Rhizome short, erect, bearing blackish-brown subulate scales up to 25 × 3 mm. Stipes 50–350 mm long, 2–4 mm diameter, stiff, pale brown at the base, green above, bearing scattered subulate scales 1–4 mm long. Laminae elliptic or rhombic to ovate, 50–450 × 35–200 mm, dark shiny green on upper surface, lighter on undersurface, stiff, erect, glabrous except for a few scattered scales, bipinnate to often tripinnate at base. Rachis green, or occasionally pale brown on undersurface, bearing a few small scattered scales. Primary pinnae in 6–17 pairs, the upper ones narrowly elliptic to narrowly ovate decreasing regularly in size towards the apex, the lower ones narrowly ovate to ovate, the longest below the middle 25–150 × 10–70 mm. Secondary pinnae on the upper primary pinnae ± linear, undivided, with obtuse apices; those on the lower primary pinnae narrowly elliptic or ovate and divided into tertiary pinnae, the longest 10–60 × 6–20 mm. Tertiary pinnae usually linear, undivided, up to 10 × 2 mm, occasionally larger and divided into 2–4 ultimate segments, apices obtuse. Sori extending along ultimate pinnules, 2–10 mm long, margins of indusia entire. Spores 34–52 × 21–37 μm; perispores prominently winged, sometimes with a few ridges.