Herb, perennial, to 50 cm tall, glabrous or sparsely pubescent; corms ca. 2.5 x ca. 3 cm. Leaves submersed or floating; submersed leaves sessile, pale green to greenish-brown, phyllodial, 0.4-0.7 x 0.4-0.8 cm, apex round acute to obtuse, basal lobes present, veins 3-5; floating leaves petiolate, petiole triangular, to 42 x 0.05-0.6 cm, basal sheath to 10 cm long, blade pale green, sagittate to hastate, 3.5-10.5 x 1.5-8.5 cm, apex round-acute, base cordate, sagittate, or hastate, basal lobes present, tips separated by 0.7-6.5 cm, veins 11-13. Inflorescence a simple scape of 1-7 whorls, floating, 0.9-9 x 0.6-4 cm, whorls with 3 flowers; peduncle terete, 10.9-22 x 0.09-0.5 cm; staminate bracts separate, delicate, elliptic to linear, 2.8-5.5 mm long, apex round, acute to obtuse; carpellate bracts separate, delicate, broadly elliptic, 9.4-15 mm long, apex obtuse; staminate pedicels spreading to erect, glabrous to densely pubescent, cylindric, 0.7-1.8 x 0.04-0.12 cm; carpellate pedicels erect to spreading in flower, spreading to reflexed in fruit, glabrous or rarely pubescent, cylindric, 0.6-2.1 x 0.12-0.21 cm. Staminate flowers: sepals erect, 5.5-10 x 3.8-5.2 mm, petals clawed, 6-8.4 x 4-6 mm, stamens 6, filaments glabrous, cylindric, ca. 1.5 x ca. 0.2 mm, anthers linear, 0.6-1.5 x ca. 0.3 mm, apex round acute, sterile carpels present. Carpellate flowers: sepals erect in flower and fruit, 4.5-10 x 2.5-10 mm, petals clawed, 8-10 x 5-7 mm, with ring of sterile stamens. Fruit aggregate 0.5-1.8 cm diam.; achenes obelliptic, 1.7-2.2 x 1.2-1.5 mm, tuberculate, without glands, with 1-3 lateral wings, margin echinate, beak lateral, erect, 0.2-0.5 mm long.
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Herbs, annual or perennial, to 50 cm; rhizomes absent; stolons absent; corms present. Leaves submersed, phyllodial, flattened, 4--7 ´ 0.4--0.8 cm, or floating; petiole triangular, to 42 cm; blade sagittate, 3.5--10.5 ´ 1.5--8.5 cm, basal lobes shorter than to equal to length of remainder of blade. Inflorescences racemes, of 1--7 whorls, floating, 0.9--9 ´ 0.6--4 cm; peduncles 10.9--22 cm; bracts distinct or connate less than ¼ total length, broadly lanceolate to linear-lanceolate, 2.8--15 mm, delicate, not papillose; fruiting pedicels spreading to recurved, cylindric, 0.6--2.1 cm. Flowers 1.2--2 cm diam.; sepals spreading in staminate, erect in pistillate, enclosing flower or fruiting head; filaments cylindric, ± equaling anther length, glabrous; pistillate pedicellate, with ring of sterile stamens. Fruiting heads 0.5--1.8 cm diam.; achenes oblanceoloid, abaxially keeled, 1.7--2.2 ´ 1.2--1.5 mm, beaked; faces tuberculate, wings 1--3, ± dentate, glands absent; beak lateral, erect, 0.2--0.5 mm.
Achenes plump, 1½-2½ by 1¼-2 mm, wings shallowly crested, occasionally smooth, faces 1-3-winged, typically strongly echinate, occasionally smooth or unadorned.
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