粗梗水蕨 cu geng shui jue

Parkeria pteridoides Hooker, Exot. Fl. 2: t. 147. 1825; Ceratopteris parkeria J. Smith, nom. illeg. superfl.

Plants usually floating, 20-30 cm tall. Stipe, rachis, and costa of lower pinnae all obviously expanded toward base, base of stipe narrowly cuneate, covered with roots. Fronds dimorphic. Sterile fronds green, smooth; stipe semicylindrical, 5-8 cm, ca. 1.5 cm in diam.; lamina ovate-triangular, simple and deeply divided, sometimes opposite-pinnate; lobes triangular to broadly loriform. Fertile fronds green when young and brownish when old, smooth; stipe 5-8 cm, 1-3 cm in diam.; lamina broadly triangular, 15-25 cm, 2-4-pinnate; ultimate lobe linear or siliquiform, 2-6 × ca. 0.2 cm, margin thin, strongly reflexed toward main vein to cover sori, apex acuminate. Sporangia attached to veinlets on both sides of main vein, covered with reflexed margin of lobe, brown, with 0-40 annulus cells, with 32 spores inside. Spore tetrahedral, below 100 μm in diam., with few parallel ridges. 2n = 78 (diploid).

Marshes, ponds, ditches, usually floating on water. Anhui, Hubei, Jiangsu, Jiangxi, Shandong [Bangladesh, India, Vietnam; Central, North, and South America].