Schoenoplectus lacustris

Ssp lacustris: Semerotu

Rhizomatous perennial. Stems stout, solitary, erect, 40-300 cm, terete, glabrous. Basal sheaths brownish, membranous, bladeless, upper sheath pale green or brown, often with short lamina. Lower bract shorter than or slightly exceeding inflorescence, 5.5-13 cm, upper bract small, setaceous. Inflorescence an unequally-rayed umbel with central spikelets in head-like clusters on shorter rays, lateral rays longer. Spikelets oblong-ovoid to ovoid, 3-16 mm. Glumes broadly obovate, 3-4.5 x 2-2.6 mm, ernarginate or notched at apex with excurrent mid-vein prolonged as short 0.3-1.5 mm awn, often fimbriate-ciliolate, reddish-brown. Perianth bristles linear-acicular, 5-6-as long as or longer than nut, retrorsely scabrid. Style c. 2.5 mm, stigmas 2-3. Nut 2-3 mm, smooth, turning brownish- or greyish-black.

1-Stems to 300 cm, green; rays usually 3 in axil of lower bract; glumes ± glabrous, without reddish-purple papillae except perhaps on awns; stigmas usually 3; nut 2.5-3 mm, flattened-trigonous ………subsp. lacustris

1-Stems usually less than 160 cm, glaucous or glaucescent; rays usually 2 in axil of lower bract; glumes red-papillose or without papillae; stigmas usually 2; nut 2-2.5 mm, plano- or bi-convex ……….subsp. tabernaemontani