Schoenoplectus tabernaemontani
Schoenoplectus purshianus
great bulrush, scirpe des étangs, soft-stem bulrush, soft-stem club-bulrush, tule
scirpe de Pursh, weak-stalk annual-bulrush, weak-stalk club-rush (bulrush)
3–10 mm diam.
cylindric, 0.5–3 m × 2–10 mm.
often arching (to decumbent), cylindric, 0.1–1 m × 0.5–2 mm.
3–4, basal;
sheath fronts membranous-translucent, often pinnate-fibrillose;
blades 1–2, C-shaped to dorsiventrally flat in cross section, usually much shorter than sheath, distal blade 2–200 × 1–4 mm, margins often scabridulous.
1, to equaling culm;
sheath fronts not pinnate-fibrillose;
blade 0 or 1, C-shaped in cross section, from a mucro to longer than a sheath, 0.5–1 mm wide, smooth.
2–4 times branched, branches to 15(–25) cm;
proximal bract usually erect, thickly C-shaped to subterete, 1–8 cm, margins sometimes scabridulous.
capitate or 1 spikelet;
proximal bract erect or often divergent, subterete-channeled, on longer culms of plant 1–15 cm and 1/30–1/3 of culm length.
15–200, solitary or in clusters of 2–4(–7), commonly all solitary, 3–17 × 2.5–4 mm;
scales uniformly dark to pale orange-brown, sometimes straw-colored, sometimes prominently lineolate-spotted, midrib often pale or green, ovate, 2–3.5 × 1.5–2 mm, sparsely (rarely densely) reddish or straw-colored, scabrous on awn and distal parts of midrib and sometimes flanks, margins ciliate, hairs contorted;
flanks veinless, apex obtuse to rounded, notch 0.2–0.3 mm deep, awn straight or bent, 0.2–0.8 mm.
1–12, 5–12 × 3–4 mm;
scales straw-colored to orange-brown, often lineolate-spotted, midrib region often greenish, broadly obovate, 2.5–3 × 2.5 mm, smooth, margins ciliolate distally, flanks in proximal part of spikelet each with 2–10 distinct ribs, apex rounded, entire, mucronate.
perianth bristles 6, brown, ± equaling achene, densely retrorsely spinulose;
anthers 2 mm;
styles 2-fid, sometimes 3-fid near spikelet apex.
perianth members 6, rarely absent, brown, bristlelike, equaling to slightly exceeding achene, distinctly wider proximally, densely retrorsely spinulose to appressed-spinulose;
anthers 0.5–0.7 mm;
styles 2-fid or 2-fid and 3-fid.
dark gray-brown when ripe, plano-convex, obovoid, 1.5–2.8 × 1.2–1.7 mm;
beak 0.2–0.4 mm.
brown, turning blackish, thickly biconvex, sometimes plano-convex or obscurely compressed-trigonous with rounded abaxial angle, abaxial face with central bulge, obovoid, proximally rounded to distinct stipelike constriction, 1.6–2.2 × 1.2–1.5 mm, base 0.3–0.4 mm wide;
beak 0.1–0.3 mm.
= 42.
Schoenoplectus tabernaemontani
Schoenoplectus purshianus
Two yellow-striped forms of Schoenoplectus tabernaemontani are grown as ornamentals.
Schoenoplectus validus, described from the Caribbean, and S. tabernaemontani, described from Europe, are here treated as one variable, cosmopolitan species without infraspecific taxa, pending further studies (J. Browning et al. 1995b; S. G. Smith 1995). Most North American plants have spikelets with reddish papillae or prickles on the scales, whereas some plants of coastal and boreal North America closely resemble most plants of northwestern Europe and southern Africa in their densely reddish prickly-papillose scales and are similar to the type of Scirpus glaucus J. E. Smith.
Schoenoplectus tabernaemontani, S. acutus, S. heterochaetus, S. lacustris, and S. triqueter belong to the very difficult S. lacustris complex. The entire complex except S. triqueter was treated as the single species Scirpus lacustris (T. Koyama 1962b). Many Old World authors treat Schoenoplectus tabernaemontani as S. lacustris var. tabernaemontani or subsp. glaucus.
Much of the local infraspecific variation in the Schoenoplectus lacustris complex is probably because of hybridization. Some studies support the recognition of separate species in this group (J. Browning et al. 1995b). Hybrids in North America include S. acutus × S. tabernaemontani, widespread and common, especially in the east; S. acutus × S. heterochaetus = S. ×oblongus (T. Koyama) Soják, widespread but uncommon; S. heterochaetus × S. tabernaemontani = S. ×steinmetzii (Fernald) S. G. Smith, eastern and most uncommon; S. tabernaemontani × S. triqueter = S. ×kuekenthalianus (Junge) Kent, lower Columbia River in Oregon and probably Washington; and S. acutus var. occidentalis × S. californicus, local in California. Except for its trigonous culms, S. triqueter is very similar to the S. lacustris complex and freely hybridizes with S. tabernaemontani, both in North America and Europe.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
Culms of Schoenoplectus purshianus have been described erroneously as trigonous (e.g., M. L. Fernald 1950). Schoenoplectus purshianus is widely confused with S. smithii; they are clearly distinct (M. Blondeau et al. 1996; S. G. Smith and E. Hayasaka 2002). Some authors (A. A. Beetle 1942b; H. A. Gleason 1952; H. A. Gleason and A. Cronquist 1963; E. G. Voss 1972–1996) have placed S. purshianus (as Scirpus) in synonymy under Schoenoplectus smithii, and most published distributions are erroneous. The taxonomic confusion is because of the subtle nature of the diagnostic characteristics of achenes and perianth bristles, the occurrence in both species of plants with or without bristles, and overlapping involucral bract lengths and frequency of divergence. No intermediates are known; although the two species occasionally grow together they are not known to hybridize. Close examination of the perianth bristles and achenes of S. purshianus and S. smithii reveals taxonomically useful but overlooked differences as stated in the key and summarized under S. smithii.
Schoenoplectus purshianus has also been confused with its close relatives in sect. Actaegeton: Schoenoplectus juncoides (Roxburgh) Palla, S. hotarui (Ohwi) Holub, and Scirpus rockii Kükenthal, which belong to the difficult “Scirpus juncoides complex” of eastern Asia, the Pacific islands, and eastern North America; Schoenoplectus purshianus should be treated as a distinct North American species pending further research (S. G. Smith and E. Hayasaka 2002).
The name Scirpus erectus Poiret has been widely misapplied to members of that complex (see 17. Schoenoplectus erectus). The names Scirpus smithii var. williamsii (Fernald) Beetle, S. juncoides Roxburgh var. williamsii (Fernald) T. Koyama, and Schoenoplectus smithii subsp. williamsii (Fernald) Soják were misapplied by their authors to both S. purshianus var. purshianus and S. purshianus var. williamsii.
Schoenoplectus purshianus var. williamsii in recent years has been treated as Scirpus purshianus forma williamsii (Fernald) Fernald. It seems better to treat the taxon as a variety rather than a form, pending further research, because it reportedly occurs in habitats with more water-level fluctuation than S. purshianus var. purshianus (A. E. Schuyler 1972; S. G. Smith and E. Hayasaka 2002) and thus may be useful as an ecologic indicator, and because form status suggests that the taxon is trivial.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Perianth bristles present. | var. purshianus |
1. Perianth bristles absent. | var. williamsii |
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