Azolla filiculoides Lam.
Pacific azolla
Plants free-floating, forming extensive red-coloured mats, up to 3 × 3 cm, broadly ovate to elliptic in outline or broader than long, irregularly branched, with secondary branchlets decreasing in length only slightly towards the distal end of primary branches. Lvs 2-lobed; upper lobe ovate, 1-2 mm long. Roots to 7 cm long, entire.
N.; S.: generally common throughout, to 600-(900) m, except for W. South Id and C. Otago.
Also indigenous to N. and S. America, Australia.
Slow moving streams, ponds and lakes.
N.Z. and Australian plants have often been referred to A. rubra R. Br. or A. filiculoides var. rubra (R. Br.) Strasburger, but these names are now generally relegated to synonymy under the widespread A. filiculoides.