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Annual, free-floating rootless heterosporous fern, overwinters only in the form of spores in sporocarps forming under senescing leaves. Shoots 3–5 cm long bear whorls of three leaves: a pair of floating leaves 12–20 mm long and a submerged, thin and filamentous leaf 3–6 cm long with numerous hairs reminding a root (rhizophyll), floating leaves densely covered by 1–1.5 mm long hairs repelling water. Three-mm large sporocarps contain either small dark brown microspores or larger whitish macrospores, membraneous prothallium ca. 2 mm large, terrestrial form known.