红纤维虾海藻 hong xian wei xia hai zao

Rhizomes creeping, ca. 5 mm in diam. Stems abbreviated, internodes 4-5 mm; persistent fibrous leaf bases reddish brown. Leaves alternate, linear, 1-1.5 m × 2-4.5 mm, 5-veined, rarely 3-veined, margin entire basally, but irregularly denticulate toward apex, apex obtuse; sheaths ca. 25 cm, amplexicaul. Spathe 1, with flattened stalk 1.2-5(-8) cm and shrimplike sheath; projections obliquely ovate to lanceolate, alternate with flowers. Anthers with 2 filiform thecae. Carpels sagittate at base. Fruit compressed, semilunate, 2.2-3 × 4-5 mm; beak apical. Fl. and fr. Apr-Oct. 2n = 16, 20.

Fine gravel or sand near low tide mark; sea level to ca. 8 m. Coasts of Hebei, Liaoning, Shandong [coasts of Japan, Korea, and Russia (Far East)].