Dig deeper at SERNEC, a consortium of southeastern herbaria.

The leafless stems are triangular in cross-section and grow 2-6 feet tall. The tallest plants are maritime; the shortest grow inland in rivers. Near the summit of each stem is a single compact cluster of spikelets, with an erect bract that looks as if it were a continuation of the stem. This species is very much like Olney's Threesquare, but ... Read more at Vascular Plants of North Carolina.

This taxon has traditionally had the name Scirpus americanus applied to it; this name, however, is properly applied to the traditional Scirpus olneyi. Schoenoplectus pungens (or Scirpus pungens) becomes the correct name for this plant (Schuyler 1974), per Weakley's Flora (2022)

SYNONYMOUS WITH PLANTS NATIONAL DATABASE:
Schoenoplectus pungens var. pungens   FAMILY Cyperaceae

SYNONYMOUS WITH Flora of North America

Schoenoplectus pungens var. pungens

SYNONYMOUS WITH Manual of Vascular Plants of NE US & Adjacent Canada (Gleason & Cronquist,1991)

Scirpus pungens var. pungens

INCLUDED WITHIN (MISAPPLIED) VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 030-08-007:

Scirpus americanus   FAMILY Cyperaceae

INCLUDED WITHIN Manual of the Southeastern Flora (Small, 1933, 1938)

Scirpus americanus

COMMON NAME:
Common Threesquare, Chairmaker's Rush, Swordgrass

NameThatPlant has no pictures at this time. You might try this link: Flora of the Southeastern United States

WEAKLEY'S FLORA OF THE SOUTHEASTERN US (4/24/22):
Schoenoplectus pungens var. pungens   FAMILY Cyperaceae

SYNONYMOUS WITH PLANTS NATIONAL DATABASE:
Schoenoplectus pungens var. pungens   FAMILY Cyperaceae

SYNONYMOUS WITH Flora of North America
Schoenoplectus pungens var. pungens

SYNONYMOUS WITH Manual of Vascular Plants of NE US & Adjacent Canada (Gleason & Cronquist,1991)
Scirpus pungens var. pungens

INCLUDED WITHIN (MISAPPLIED) VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 030-08-007:
Scirpus americanus   FAMILY Cyperaceae

INCLUDED WITHIN Manual of the Southeastern Flora (Small, 1933, 1938)
Scirpus americanus