Schizaea australis Gaudich.

Rhizomes short-creeping; bearing glossy, chestnut-brown, septate hairs, 1–3 mm long. Fronds 20–250 mm long, rarely to 350 mm long in sheltered lowland areas, 2–5 mm wide. Sterile portion of frond undivided, erect, 15–245 mm long, rarely to 345 mm long in sheltered lowland areas, ±terete, furrowed on one side, 0.25–0.5 mm diameter, green or pale brown, glabrous or with scattered hairs; stomata on sterile portion of frond 81–114 μm long. Fertile portion of frond pinnately divided, 3–12 mm long, rarely to 17 mm long, 1–4 mm wide; fertile branches infolded, in 4–13 pairs, 1–5 mm long, with fimbriate margins. Sporangia borne in one row either side of midrib of fertile branches, 4–8 per branch; hairs absent amongst sporangia.

Schizaea australis is closely related to S. fistulosa but differs in its shorter fronds (20–350 mm cf. 115–570 mm long), shorter fertile portions of the frond (3–17 mm cf. 9–38 mm long), fewer pairs of fertile branches (4–13 cf. 7–30 pairs), its montane and more southerly distribution, and its generally more slender habit and twisted sterile portions of the frond. The distributions of the two species overlap on Great Barrier Island, Mt Moehau, and in north-west Nelson, but only in north-west Nelson are populations frequently found in the same altitudinal range. S. fistulosa is distinct from S. australis in having twice as many chromosomes (n = c.190 cf. n = 94). This ploidy difference is reflected in the size of the guard cells of the stomata, which are arranged in long vertical lines on the sterile portions of the frond and are visible under a dissecting microscope. The guard cells are 126–180 μm long in S. fistulosa compared with 81–114 μm long in S. australis (Brownsey & Perrie 2013).

Normally a terrestrial fern that occurs from lowland to subalpine areas, favouring boggy ground in tussock, short grassland, herbfield, Gleichenia fernland, turf vegetation or open scrub and podocarp forest, but also in seepages and at the side of tarns. It can also occur on near vertical mossy banks and rock faces. On Table Mountain, Coromandel and Mt Hobson, Great Barrier Island, it is epiphytic on Metrosideros and Agathis in open forest in extremely boggy areas. At lower elevations it is found on pākihi soils.

There is some cytological evidence for hybridisation between S. australis and S. fistulosa (Brownsey et al. 1985). Lash (1966) reported n = 94 for several populations of S. australis from north-west Nelson, and n = c.150 for other populations from the same area with generally larger plants. Reinterpretation of Lash’s illustrated cell suggested the presence of at least some univalents (Brownsey et al. 1985), and the possibility of hybridisation causing failure of pairing. A chromosome count of n = c.190 has been reported for S. fistulosa from Auckland (Brownsey et al. 1985; Dawson et al. 2000). Lash’s count of c.150 is consistent with the possibility of hybridisation between S. fistulosa and S. australis in north-west Nelson where both species are known to occur.

n = 94 (Brownlie 1965; Lash 1966).