Roots absent. Fronds submersed (except when flowering or fruiting), proximal part near surface, 1 or 2--20 or more, coherent, linear, ribbon-, sabre- or tongue-shaped, or ovate, flat, longer than 2 mm, margins entire; air spaces in tissue; pouch 1, terminal, at base from which daughter fronds (no flowers) originate, triangular, lower wall of pouch with tract of elongated cells forming connection between node and attachment to mother frond; veins 0; scale at base of frond absent; anthocyanins absent; pigment cells present (visible in dead fronds as brown dots); turions absent. Flowers 1(--2) per frond, originating in cavity at side of median line of upper frond surface, not surrounded by utricular scale; stamen 1, 2-locular. Seeds 1, nearly smooth. x = 10, 20, 21.

Thallus minute, not over ca 1.5 mm, thickened, globose to ellipsoid or ovoid, or flattened on the upper side only, without veins or roots; reproductive pouch solitary, on the upper surface near the basal end, to one side of the midline; reproduction almost entirely by budding, the young plants soon detached; fls (rarely produced) without a spathe, paired, one of each sex, the pistillate one nearer the base, with a single orthotropous ovule; anther unilocular, opening across the top. 8, cosmop. The smallest angiosperm.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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