20 Fig. 6 FERNS <strong>and</strong> ALLIED PLANTS FDRV1 March 2011
A. pinnata R. Br. Plants free-floating, regularly branched, somewhat triangular in outline, to c. 3 cm long; roots <strong>of</strong> mature <strong>plants</strong> feathery. Leaves with lobes c. 1 mm long; upper lobe green or reddish, upper surfaces papillate except for the somewhat membranous margins; lower lobe brownish <strong>and</strong> scale-like. Massulae more or less conical <strong>and</strong> basally with 1–6 unbarbed processes. Fertile <strong>plants</strong>: not seen. Fig. 6 (Wilson, DNA 127104); Pl. 5 (unvouchered). FERNS <strong>and</strong> ALLIED PLANTS 21 AZOLLA Lam. SCHIZAEACEAE D.J. Dixon Asia, New Caledonia, New Guinea, New Zeal<strong>and</strong> <strong>and</strong> Australia (S.A., N.T., Qld, N.S.W., Vic.). In the N.T. confined to the Top End. A common species in still <strong>and</strong> slow-moving waters, e.g. at Fogg Dam <strong>and</strong> floodplains <strong>of</strong> the Mary <strong>and</strong> Finniss rivers. Plants are usually red or red-brown when growing on open water <strong>and</strong> greenish in shaded places. They usually multiply by fragmentation. Homosporous terrestrial <strong>ferns</strong>. Rhizome short or long-creeping <strong>and</strong> clothed with septate hairs, roots wiry. Fronds circinnate, exstipulate, dimorphic. Stipe grading into lamina, indistinct. Sterile lamina undivided or dichotomously branched once to many times; segments narrow, linear; veins free; fertile lamina similar to sterile but with sporogenous segments borne pinnately or digitately at the apex <strong>of</strong> lamina axes which are undivided or dichotomously branched, separate or rarely joined by intercostal lamina tissue. Sporangia in 1 or more rows, on either side <strong>of</strong> the vein, intermixed or not with long hairs. Spores ellipsoidal. A family consisting <strong>of</strong> two genera with c. 41 species, seven species in Australia, three in the D.R. Taxonomic reference: Chinnock (1998g). 1 Fertile segments digitately arranged; lamina unbranched ...................................... Actinostachys 1: Fertile segments pinnately arranged; lamina dichotomously branched ............... Schizaea ACTINOSTACHYS Wall. Terrestrial <strong>ferns</strong>. Rhizome short-creeping, clothed with simple or multicellular hairs, roots wiry. Fronds simple, dimorphic, flattened or terete. Stipe grading into lamina, indistinct. Sterile lamina undivided; fertile lamina similar to sterile but with apical sporogenous segments. Sporogenous lobes with constriction at point <strong>of</strong> attachment. Sporangia in 2 or 4 rows, on either side <strong>of</strong> the vein. Spores ellipsoidal, smooth or with tubercles. A genus <strong>of</strong> c. 13 species, two <strong>of</strong> which are found in Australia, including the N.T. 1 Sporangia in 4 rows, not interspersed with hairs; lamina constricted below sporogenous lobes ........................................................................................................ A. digitata 1: Sporangia in 2 rows, interspersed with brown hairs; lamina not constricted below sporogenous lobes ............................................................................................ A. wagneri A. digitata (L.) Wall. Acrostichum digitatum L. Rhizome short-creeping or suberect, clothed with long stiff glossy pale brown hairs. Fronds clustered, linear-flattened, erect to sinuously erect, grass-like, 8.5–41 cm long, 1.6–4 mm wide; surface smooth, dull to slightly shiny, constricted below sporogenous lobes; midrib prominently raised on 1 side, margins flat to recurved. Sporogenous lobes 3–18, linear, tufted at apex, 8– 54 mm long, to 0.5 mm wide, occasionally with some branches forked distally. Sporangia in 4 rows. Fertile <strong>plants</strong>: all year. Fig. 7 (Dunlop 7540; Michell 1503). FDRV1 March 2011