The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

American bulrush, chair-maker's rush, chairmaker's clubrush, common three-square, common three-square bulrush, schoenoplectus, scirpe acere, three-square club-bulrush, western bulrush

American bulrush, chair-maker's club-bulrush, chairmaker's bulrush, Olney bulrush, Olney's bulrush, Olney's three-square bulrush, schoenoplectus


often vertical, 1–6 mm diam., firm to hard;

scales shorter to longer than internodes, disintegrating to fibers.

2–5 mm diam.


sharply trigonous, sides convex to concave proximally, deeply concave to flat distally, 0.1–2 m × 1–6 mm, smooth.

sharply trigonous, sides deeply concave throughout to rarely nearly flat, 0.4–2.5 m × 3–10 mm.



sheath fronts membranous distally, orifice adaxially truncate to concave, often splitting;

ligules 2-fid, 1 mm;

blades 2–6, proximally V-shaped, distally trigonous to asymmetrically laterally flattened in cross section, angles often scabridulous distally;

distal blade (1–)2–5 times as long as sheath, 50–750 × 2–9 mm.

ca. 3, basal, less than 1/2 culm length;

sheath fronts not pinnate-fibrillose;

blades 1–3, V-shaped near base, otherwise laterally flattened-trigonous in cross section;

distal blade 0.2–1.5 times as long as sheath, 25–200 × 2–8 mm.



proximal bract usually erect, resembling leaf blade but trigonous proximally, (1–)3–20 cm.

capitate or very rarely with 1 branch to 5 mm;

proximal bract usually erect, resembling leaf blade, 1–6 cm.


1–5(–10), 5–23 × 3–5(–7) mm;

scales bright (to very dark) orange-, red-brown, or purplish brown to straw-colored, often prominently lineolate-spotted, midrib mostly paler, ovate, 3.5–6 × 2–3 mm, smooth or awn sparsely spinulose, margins deciduously ciliolate, flanks ribless except sometimes proximal scales, midrib prominent, apex acute (to obtuse), 2-fid, notch (0.3–)0.5–1 mm deep, awn mostly irregularly bent, 0.5–1.5(–2.5) mm.

2–20, 5–15 × 3–5 mm;

scales bright orange- to red- or purple-brown to straw-colored, often partly translucent, usually clearly lineolate-spotted, broadly ovate, 2.7–4 × 2–3 mm, smooth or awn sparsely spinulose, margins deciduously ciliolate, flanks of proximal scale often with several ribs, apex rounded to acute, notch 0.1–0.4 mm deep, awn not contorted, 0.2–0.6 mm.


perianth members 4–8, sometimes fewer, brown, bristlelike, variably slender to stout, equal or unequal, all equaling achene body to all rudimentary, retrorsely spinulose;

anthers 2–3 mm;

styles 2–3-fid.

perianth members (2–)5–6(–7), yellow-brown, bristlelike, slender to stout, often unequal to equaling 1/2 achene body, retrorsely spinulose;

anthers 1.5–3 mm;

styles 2-fid or 2-fid and 3-fid.


brown, biconvex to compressed bluntly trigonous, obovoid to obpyriform, (2–)2.5–3.5 × 1.3–2.3 mm;

beak 0.1–0.5 mm.

brown when ripe, thickly plano-convex or unequally biconvex or compressed obtusely trigonous, obovoid, 1.8–2.8 × 1.3–2 mm;

beak 0.1–0.3 mm.


= 74, 78.

= 78.

Schoenoplectus pungens

Schoenoplectus americanus

Phenology Fruiting spring–summer (south), summer (north). Fruiting spring–summer (south), summer (north).
Habitat Fresh to brackish shores, marshes, lakes, fens, often emergent in water to 0.7 m Brackish or mineral-rich shores, marshes, fens
Elevation 0–2400 m (0–7900 ft) 0–2200 m (0–7200 ft)
from FNA
AK; AL; AR; AZ; CA; CO; CT; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; SC; TX; UT; VA; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; ON; PE; QC; SK; Mexico; South America; West Indies; Europe; Australia (including Tasmania); New Zealand
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AZ; CA; CT; DE; FL; GA; ID; KS; LA; MA; MD; ME; MI; MO; MS; NC; NH; NJ; NM; NV; NY; OK; OR; RI; SC; TX; UT; VA; VT; WA; WY; BC; NS; Mexico; Central America; South America; West Indies (Puerto Rico)
[WildflowerSearch map]
[BONAP county map]

Three varieties of Schoenoplectus pungens (under Scirpus americanus) were recognized for North America by T. Koyama (1963), and three more or less equivalent varieties were recognized by S. G. Smith (1995). These varieties are described informally and illustrated here but not formally recognized because their morphologic delimitation should be evaluated and their exact ranges are still uncertain.

Schoenoplectus pungens (Vahl) Palla var. pungens has brown to straw-colored spikelet scales, bifid styles, and lenticular achenes. It is the only variety that occurs in Europe and North America. In North America, it extends from the Atlantic Coast to Saskatoon and is reported from Arkansas, Kansas, Louisiana, Minnesota, and Missouri.

Schoenoplectus pungens (Vahl) Palla var. longispicatus (Britton) S. G. Smith has bright orange to reddish (or purplish) brown or often stramineus and lineolate-spotted spikelet scales, trifid styles, and trigonous to lenticular achenes. Endemic to the flora area, variety longispicatus occurs in western North America, except Pacific Coast, east to Saskatoon, Manitoba, and Ontario, along the north shore of Lake Superior, south to Iowa, Minnesota, western Wisconsin, Missouri, and southern Mississippi.

Schoenoplectus pungens (Vahl) Palla var. badius (J. Presl & C. Presl) S. G. Smith has uniformly dark chestnut spikelet scales, trifid styles 3-fid, and trigonous or thickly biconvex achenes. In North America, variety badius occurs along the Pacific Coast (to slightly inland) from British Columbia south to California. Outside the flora area it occurs in Baja California, Mexico, temperate South America, Australia, including Tasmania, and New Zealand.

The name Scirpus americanus [subsp. monophyllus (J. Presl & C. Presl) T. Koyama] var. monophyllus was misapplied to Schoenoplectus pungens var. badius (T. Koyama 1963). The type of the basionym Scirpus monophyllus J. Presl & C. Presl from Peru belongs to Schoenoplectus americanus (S. G. Smith 1995).

Schoenoplectus americanus, S. pungens, and S. deltarum belong to the small “Scirpus americanus complex” T. Koyama (1963), in which the species are sometimes difficult to delimit. Schoenoplectus pungens was long known incorrectly as S. americanus Persoon; the type of that name is conspecific with plants formerly treated as S. olneyi A. Gray (A. E. Schuyler 1974). Putative Schoenoplectus pungens × S. americanus hybrids [= S. ×contortus (Eames) S. G. Smith] are locally common. 2n = ca. 86–128.

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

The secondary involucral bracts of Schoenoplectus americanus lack blades and closely resemble floral scales, in contrast to S. pungens and S. deltarum. Although mostly very locally distributed, S. americanus is ecologically important in many coastal marshes. In recent years it has seriously declined (e.g., in Maryland and Louisiana). It may occur in southwestern Kansas; I have not seen a specimen. It probably has been extirpated from the Missouri station, based on one collection from 1886 (G. Yatskievych, pers. comm.). The report from New Hampshire is based on M. L. Fernald (1950). The stations on the Maine and Connecticut coasts, at Lake Champlain in Vermont, and in Oklahoma are based on putative S. americanus × S. pungens specimens. Some plants in the southwest are atypical in having nearly flat culm sides and leaf blades to 1.5 times as long as their sheaths as in the type of Scirpus monophyllus J. Presl & C. Presl from Peru. The name Scirpes americanus was long misapplied to Schoenoplectus pungens; Schoenoplectus americanus was known as Scirpus olneyi (A. E. Schuyler 1974).

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

Source FNA vol. 23, p. 51. FNA vol. 23, p. 52.
Parent taxa Cyperaceae > Schoenoplectus > sect. Schoenoplectus Cyperaceae > Schoenoplectus > sect. Schoenoplectus
Sibling taxa
S. acutus, S. americanus, S. californicus, S. deltarum, S. erectus, S. etuberculatus, S. hallii, S. heterochaetus, S. mucronatus, S. purshianus, S. saximontanus, S. smithii, S. subterminalis, S. tabernaemontani, S. torreyi, S. triqueter
S. acutus, S. californicus, S. deltarum, S. erectus, S. etuberculatus, S. hallii, S. heterochaetus, S. mucronatus, S. pungens, S. purshianus, S. saximontanus, S. smithii, S. subterminalis, S. tabernaemontani, S. torreyi, S. triqueter
Synonyms Scirpus pungens Scirpus americanus, Scirpus olneyi
Name authority (Vahl) Palla: Verh. K. K. Zool.-Bot. Ges. Wien 38(Sitzungsber.): 49. (1888) (Persoon) Volkart ex Schinz & R. Keller: Fl. Schweiz ed. 2, 1: 75. (1905)
Web links