Allisoniella nigra (Rodway) R.M.Schust.
Allisoniella nigra subsp. novaezelandiae R.M.Schust., Nova Hedwigia 22: 143. 1972 (1971).
Holotype: New Zealand, North Is., Waipoua River, N of Dargaville, Schuster 63-1891 (herb. Schuster).
Allisoniella obcordata E.A.Hodgs., Trans. Roy. Soc. New Zealand, Bot. 3: 80. 1965.
Holotype: New Zealand, North Is., Waipoua River, Allison H919 (MPN, Hodgson hb. No. 6165, non vidi).
Plants rigid, suberect to erect, with wiry stems, brownish to fuscous where not decolorate, the leafy stems 800–950 µm wide. Leaves strongly and stiffly spreading, remote to contiguous, unistratose except sometimes in one tier at stem juncture, nearly flat on weaker (and especially ♂) shoots, on vigorous stems the leaves with lobes distinctly abaxially concave (with decurved margins) or (in extreme cases) sulcate, the leaves broadly orbicular-quadrate, always wider than long, (300)380–450 × (425)525–580 µm to 440–540 × 580–700 µm, in vegetative sectors with sinus varying from very slight, the leaves merely broadly retuse to bilobed to 0.1–0.55; lobes very wide (as wide as to much wider than long), 20–32 cells wide, the summit narrowly to more often broadly rounded and becoming semicircular; sinus occasionally gibbous; lamina margins broadly rounded at the base, sometimes cordate. Cells with walls thickened but not strongly so (the lumina remaining angular), the marginal cells subquadrate, usually 10–13 µm wide, the median cells 15–17 µm wide × 17–20(24) µm long; surface smooth or nearly so. Gemmae unknown (except in fo. subobtusa).
Autoecious. Androecia eventually intercalary on long leafy axes that often have reduced sterile leaves, compactly spicate, with 5–7 pairs of bracts; bracts closely imbricate, pouched, shallowly bilobed (sinus descending to 0.1–0.15), lobes broadly rounded, appressed to bract lying anterior. Gynoecia terminating long leafy axes, with leaves gradually larger and grading into bracts; innermost bracts broadly orbicular, almost reniform, wavy, bilobed to 0.25, the lobes broadly but shallowly abaxially concave, broadly rounded, semicircular. Perianth to 0.75 emergent at maturity, oblong in outline, at most feebly contracted to the truncate mouth, deeply (4)5-plicate in distal 0.6–0.75, the plicae compressed (perianth cross sections, above, cruciate or stellate), the mouth becoming bleached and decolorate, crenulate or crenulate-denticulate.
Sporophyte unknown.
Comments : This taxon, whatever its rank, is “clearly autoecious” (Schuster, 1972a, p. 144); the very similar Allisoniella obcordata is described by Hodgson (1965) as dioecious and with perianths 5-plicate. Schuster (1972a) examined a fragment of the type of A. obcordata and remarked (p. 144) “in the fragments I have seen androecial and gynoecial branches are obviously intermingled and I suspect the plant may prove to be autoecious, rather than dioecious as Hodgson describes.... No connection could be demonstrated between the long sexual branches, however.” If the inflorescence differences actually exist, two taxa may be at hand.
Two forms have been recognized in the literature.
