Schoenoplectus subterminalis
Swaying bulrush, Water bulrush, Water clubrush
Scirpus subterminalis Torrey
Slender perennials to about 1 m tall, forming mats from long, slender rhizomes to 1 mm in diameter, tubers sometimes present, plants usually submerged except for emergent inflorescences or entirely submerged and without inflorescences; culms slender, subcylindric, 20–80 (150) cm long and to 1 mm thick, flaccid if submerged with the distil portion floating, or rarely terrestrial with culms firm and erect.
3–20 or more; sheaths smooth, less than half the stem height, fronts sometimes splitting leaving delicate fibers that often separate and resemble the blades; submerged blades flaccid, filiform to narrowly ribbon-like and floating; erect blades firm and C-shaped in cross-section proximally and elliptic distally, 0.2–1 mm wide, 1.5-6 dm long, longer than the sheaths but difficult to distinguish from them.
Solitary, erect, prominent, sheathless, appearing as a continuation of the culm, apex acute, 7–60 mm long, greatly exceeding the inflorescence.
A solitary, erect spikelet, oblong to oblong-cylindric, few to many- flowered, upper slender portion consists of staminate flowers, light brown, 5–15 mm long, 3–7 mm wide.
Ovate to lanceolate, thin and almost hyaline, smooth, pale brown, midrib region firm and greenish when young, margins sometimes minutely cilitate; apex not notched but with a minute mucro, greenish, 4–6 mm long, 1.5 mm wide.
Perfect; perianth bristles 6, retrorsely spinulose, brown, shorter than to about as long as achene (including the beak); stamens 3; styles trifid.
Obovoid, markedly trigonous, smooth, pale to dark brown, 2.5–3.5 mm long (including the prominent 0.3–0.8 mm long beak), 1.5–1.7 mm thick.
Fruiting: July–August.Shallow water in fresh oligotrophic lakes and streams from sea level to 2300 m elevation. Rare or local in most of its range. In the Intermountain Region it is known from Fremont, Valley, and Elmore Counties in Idaho, and from a single Utah report. Collections have also been made in Dolores and San Juan Counties, Colorado, near the southeastern border of Utah. The species is disjunct in western and eastern North America: In the West from southeastern Alaska and British Columbia south to northern Idaho and northern California; in the East from Minnesota to Labrador and south to Missouri, South Carolina and the Florida panhandle.
Eleocharis acicularis (when aquatic, robust, and without inflorescences): Leaf blades absent. Note: In delicate aquatic forms of S. subterminalis, the leaves are often difficult to distinguish from the culms, and in Eleocharis acicularis, the culms may closely resemble leaves.
