Aerial
stems 1–4 m tall. Leaves 8–15 mm wide, about as long as the aerial stems, the
basal sheaths truncate or tapering above, not or only slightly auriculate, the
mucilage glands brown, extending 1–10 cm up the inner surface of the leaf
blades. Spikes 20–40 cm long, the staminate and pistillate portions separated
by 1–8 cm of sterile stem. Pistillate portions of the spikes 2–3 cm in diameter
in fruit, brown to yellowish brown. Pistillate flowers subtended by linear‑acuminate
bracts with unthickened, light brown tips, the stigmas linear to linear‑lanceolate,
the stalks with white, filiform hairs slightly thickened and brown toward the
tips. Fruits (including stalks and hairs) 5–8 mm long. 2n=30. May–July.
Uncommon
in the Unglaciated Plains Division (worldwide except Australia, New Zealand, mostly tropical). Emergent aquatic, on margins of ponds and intermittent
drainages in mesic prairies.
The
presence of this species in Missouri has only recently been confirmed. It is
common in the southern Great Plains and occurs in several counties in Kansas that are adjacent to Missouri, thus it presumably occurs natively in the state. It
should be searched for elsewhere in the prairies of western Missouri.
For
a discussion of the hybrid with T. angustifolia, see the treatment of
that species.