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

Smith's annual-bulrush, Smith's bulrush

Habit Plants annual; rhizomes 1 mm diam.

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

scales shorter to longer than internodes, disintegrating to fibers.


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

often arching (to decumbent), terete, 0.02–0.5 m × 0.5–1.5 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.

1, to equaling culm;

sheath fronts not pinnate-fimbrillose;

blades 0–1, cross section C-shaped, from a mucro to longer than a sheath by 0.5 mm, smooth.



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

capitate or 1 spikelet;

proximal bract erect, very rarely divergent, on longer culms of plants 5–150 mm and 1/5–2/3 culm length.


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.

1–15, 5–12 × 3(–4) mm;

scales straw-colored to orange-brown, often lineolate-spotted, midrib region usually green becoming straw-colored, obovate, 2.5–3 × 1.5–2 mm, smooth, margins distally ciliolate at 20X, flanks in proximal part of spikelet each with 2–10 distinct ribs, apex rounded, entire, mucronate.


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 bristles 0 or 4–6, rarely 1–3, brown, ± equaling to 2 times longer than achene, rarely much shorter, slender throughout, densely to sparsely retrorsely-spreading spinulose;

anthers 0.4–0.6 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, turning blackish, thinly to thickly plano-convex or unequally biconvex, sometimes clearly trigonous with distinct, narrow abaxial angle, adaxial face without central bulge, cuneate-obovoid, proximally evenly tapered and usually without stipelike constriction, 1.5–2 × 1.2–1.5 mm, base 0.2–0.3 mm wide;

beak 0.1–0.2 mm, very finely longitudinally ridged at 20–30X.


= 74, 78.

Schoenoplectus pungens

Schoenoplectus smithii

Phenology Fruiting spring–summer (south), summer (north).
Habitat Fresh to brackish shores, marshes, lakes, fens, often emergent in water to 0.7 m
Elevation 0–2400 m (0–7900 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
[WildflowerSearch 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.)

Varieties 3 (3 in the flora).

Plants of Schoenoplectus smithii with perianth bristles are easily disinguished from S. purshianus by the uniformly slender bristles in S. smithii; plants without bristles may be identified using the achene characters as indicated in the key. In addition, in S. smithii the receptacle collar is relatively small, the achenes are usually widest distal to the middle, the summit is often subtruncate, the adaxial face is often plane, the abaxial face is without a central bulge and sometimes has a distinct narrow angle, and when mature the surface has fine longitudinal ridges. In contrast, in S. purshianus the receptacle collar is relatively large, the achenes are usually widest at the middle, the summit is usually rounded, the adaxial face is nearly always convex, the abaxial face has a distinct central bulge and never a narrow angle, and the surface lacks fine longitudinal ridges.

The eastern Asian Scirpus komarovii Roshevitz [= Schoenoplectus komarovii (Roshevitz) Soják] was treated as Scirpus smithii var. leiocarpus (Komarov) T. Koyama (= Schoenoplectus smithii subsp. leiocarpus Soják) by T. Koyama (1962b); it is better to treat S. komarovii as a distinct Asian species and S. smithii as restricted to North America pending further research (S. G. Smith and E. Hayasaka 2002).

The varieties of Scirpus smithii were reduced to S. smithii forma setosus (Fernald) Fernald and S. smithii A. Gray forma levisetus (Fassett) Fernald (M. L. Fernald 1942). It seems better to treat those taxa as ecotypic varieties following W. R. Ferren Jr. and A. E. Schuyler (1980) because they reportedly grow in different habitats (S. G. Smith and E. Hayasaka 2002) and thus may be valuable as ecologic indicators. The varieties are undoubtedly more widely distributed than given here; distributions were based on specimens I have seen and reports by A. E. Schuyler (1972) and W. R. Ferren Jr. and A. E. Schuyler (1980).

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

1. Perianth bristles absent or rudimentary.
var. smithii
1. Perianth bristles present, some well developed.
→ 2
2. Perianth bristles 4–6, equaling to twice as long as achene, densely spinulose.
var. setosus
2. Perianth bristles 1–4, much shorter than to nearly equaling achene, smooth or very sparsely spinulose.
var. levisetus
Source FNA vol. 23, p. 51. FNA vol. 23, p. 56.
Parent taxa Cyperaceae > Schoenoplectus > sect. Schoenoplectus Cyperaceae > Schoenoplectus > sect. Actaeogeton
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. americanus, S. californicus, S. deltarum, S. erectus, S. etuberculatus, S. hallii, S. heterochaetus, S. mucronatus, S. pungens, S. purshianus, S. saximontanus, S. subterminalis, S. tabernaemontani, S. torreyi, S. triqueter
Subordinate taxa
S. smithii var. levisetus, S. smithii var. setosus, S. smithii var. smithii
Synonyms Scirpus pungens Scirpus smithii
Name authority (Vahl) Palla: Verh. K. K. Zool.-Bot. Ges. Wien 38(Sitzungsber.): 49. (1888) (A. Gray) Soják: Cas. Nár. Mus., Odd. Prír. 141: 62. (1972)
Web links