Marsilea L.

Nardoo

8 species native AUST.; all states and territories except Tas.

Growing in grassland on the edges of swamps, weirs, rivers or waterholes, floating on shallow water or rooting in the mud on the banks, usually occurring on land which is subject to periodic inundation. Sterile fronds borne at intervals along the rhizome on long stalks; the lamina composed of 2 pairs of opposite, obovate, glabrous or hairy leaflets. Veins fine, very numerous, radiating from the base of the leaflet, reticulate but without free vein-endings in the long narrow areolae. Sporocarps borne on stalks which arise at intervals along the rhizomes, solitary or in groups, hard, woody, usually densely hairy, often ribbed, globose or oblong-ovoid or ellipsoid or almost square, usually bearing 1–2 basal teeth which are conical, flat-topped or hooked, sometimes without teeth. Sori attached to a gelatinous ring which is later exserted when the sporocarp bursts.