Blechnum deltoides
(Colenso) T.C.ChambersRhizome spreading to semi-erect, short, coarse. Fronds tufted, erect, firm in texture, 20–50 cm tall; sterile and fertile fronds dissimilar. Stipe long, dark and very rough at base, paler and smoother towards rachis; scales dense near base, growing from tubercles which harden, shiny, red-brown, narrow, tapering to fine, twisted tips; fine hairs present. Sterile frond lamina narrowly wedge-shaped, once pinnate, dark green, under-surface with fine hairs; pinnae close-set, attached by broad bases, lowest pair curved and slightly deflexed, others straighter, broad, with pointed tips; margins clear, thickened, crinkled to entire. Fertile fronds erect, similar in length to sterile fronds; pinnae narrow and curved, bases widened. Sori covering underside of lamina on each side of midvein.
HSF, VAlp. Also Tas. New Zealand. Known on the mainland only from a few sites near Bryces Gorge, Snowy Range, where it was first recorded in 1980 growing among rocks on wet peaty ground in a steep, shaded gully.
Blechnum deltoides was previously included in B. vulcanicum (Blume) Kuhn. Blechnum vulcanicum in this broad circumscription encompassed considerable morphological variation and occurred in Malesia through to the islands of the tropical Pacific, with disjunct occurrences in Victoria, Tasmania and New Zealand. A revision conducted by Chambers & Wilson (2019) recognised 13 species that were related to or had been included in B. vulcanicum s.lat., including B. deltoides. Based on this treatment B. vulcanicum s.str. is confined to high altitude sites throughout Malesia. Blechnum deltoides differs from B. vulcanicum s.str. by its lamina segments being pilose on the abaxial surface only rather than both surfaces. Results from phylogenetic analyses of chloroplast DNA sequences (rbcL, rps4–trnS, trnL–trnF) have so far supported this revision (Perrie et al. 2014). Blechnum deltoides populations in Australia and New Zealand possessed very similar sequences for the sampled regions, supporting the recognition of these populations as conspecific and other species sampled from the B. vulcanicum group such as B. hirsutum Rosenst. and B. pilosum (Brack.) Brownlie, formed a lineage with B. deltoides but all three species had sequences that differed substantially from each other (Perrie et al. 2014), which supports recognising these taxa as separate species.
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