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scirpe subterminal, swaying bulrush, swaying clubrush, water annual-bulrush, water bulrush, water club-rush

Habit Plants mat-forming; rhizomes to 1 mm diam; terminal tubers sometimes present, to 3 mm thick, fleshy.
Culms

subcylindric, 0.2–1.5 m × 0.5–1 mm.

Leaves

3–20+, smooth;

sheath fronts sometimes delicately pinnate-fibrillose;

blades 3–20, when erect C-shaped in cross section proximally, elliptic most of length, when submerged usually flaccid and filiform to narrowly ribbonlike, probably longer than sheath, 0.2–1 mm wide.

Inflorescences

a solitary, erect spikelet;

proximal bract erect, like stiff leaf blade, 7–60 mm.

Spikelets

5–15 × 3–7 mm;

scales pale brown, or central region green when young, ovate-lanceolate, 4–6 × 1.5 mm, smooth, margins sometimes ciliolate apically at 40X, midrib obscure, apex acute, entire, minutely mucronate.

Flowers

perianth members 6, brown, bristlelike, from 1/2 of to equaling achene beak, spinulose;

anthers 2–3.5 mm;

styles 3-fid.

Achenes

brown, strongly trigonous, obovoid to obpyriform, (2.5–)3–3.5 × 1.5–1.7 mm;

beak 0.3–0.8 mm.

2n

= 72.

Schoenoplectus subterminalis

Phenology Fruiting summer.
Habitat Submerged to emergent in water to 1 m or sometimes terrestrial, fresh lakes, streams, bogs
Elevation 10–2200 m (0–7200 ft)
Distribution
from FNA
AK; AL; CA; CT; DE; FL; GA; ID; IL; IN; MA; MD; ME; MI; MN; MO; MT; NC; NH; NJ; NY; OH; OR; PA; RI; SC; UT; VA; VT; WA; WI; BC; NB; NL; NS; ON; PE; QC; SK
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Discussion

Schoenoplectus subterminalis often forms lawnlike, underwater mats that are entirely vegetative or have only the inflorescences emergent. This species is probably extirpated from Illinois. Schoenoplectus subterminalis var. terrestris Paine [= S. subterminalis forma terrestris (Paine) Fernald] probably does not deserve taxonomic recognition.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23, p. 54.
Parent taxa Cyperaceae > Schoenoplectus > sect. Malacogeton
Sibling taxa
S. acutus, S. americanus, S. californicus, S. deltarum, S. erectus, S. etuberculatus, S. hallii, S. heterochaetus, S. mucronatus, S. pungens, S. purshianus, S. saximontanus, S. smithii, S. tabernaemontani, S. torreyi, S. triqueter
Synonyms Scirpus subterminalis
Name authority (Torrey) Soják: Cas. Nár. Mus., Odd. Prír. 140: 127. (1972)
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