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Published In: Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 38: 49. 1888. (Mar 1888) (Verh. K.K. Zool.-Bot. Ges. Wien) Name publication detailView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 9/1/2009)
Acceptance : Accepted
 

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13. Schoenoplectus (Rchb.) Palla (bulrush)

(Smith and Yatskievych, 1996)

Plants perennial with rhizomes or apparently annual and tufted. Aerial stems few to usually many per plant, erect to ascending, slender to stout, unbranched, glabrous, circular or 3-angled in cross-section, often finely ridged. Leaves basal or few and alternate below the middle of the stems, the lowermost 1–3 reduced to bladeless sheaths, glabrous. Leaf sheath tips mostly strongly oblique with a V-shaped or U-shaped sinus on 1 side, the ligule present, appearing as a short, white, scaly ridge (or sometimes a thin, white margin at the tip of bladeless sheaths). Inflorescences appearing lateral, subtended by 1–3 bracts, the main bract erect and stemlike, composed of 1 to many spikelets, these sessile or nearly so in a headlike cluster, or in an uneven umbel of several stalked spikelets or clusters of spikelets. Florets usually 10 to many per spikelet, in an overlapping spiral pattern, perfect. Spikelet scales ovate to broadly ovate, the tips rounded to pointed and often with a shallow notch, the midrib usually extended past the main body of the scale as a short awn. Perianth bristles 2–6 or absent. Stamens 2–3. Styles not expanded at the base during flowering, not forming a tubercle, but frequently persisting on the fruit as a short beak. Stigmas 2 or 3. Ovaries and fruits naked, without a perigynium (saclike covering). Fruits biconvex, sometimes unequally so (1 side more rounded than the other), or 3-angled. About 40 species, nearly worldwide.

Schoenoplectus has been included in the genus Scirpus in most of the North American botanical literature. For further discussions of the segregation of genera from Scirpus, see the treatment of that genus and the review of Missouri bulrushes by Smith and Yatskievych (1996). The presence of several interspecific hybrids in the genus can confuse determinations. These hybrids generally have been collected infrequently in Missouri but can be relatively common at sites where two or more species of Schoenoplectus grow together.

The seeds of Schoenoplectus species provide food for waterfowl, which disperse these bulrushes both in mud on their feet and feathers and as undigested seeds in their droppings.

 

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1 Stems triangular in cross-section (2)
+ Stems round in cross-section or somewhat flattened (7)
2 (1) Inflorescence with some or all of the spikelets stalked 4 Schoenoplectus etuberculatus
+ Inflorescence with the spikelets all sessile in a headlike cluster (3)
3 (2) Plants annual or apparently so, the short rhizomes, if present, hidden by the tufted stem bases 7 Schoenoplectus mucronatus
+ Plants perennial with noticeable, creeping rhizomes, the stems spaced along the rhizome (sometimes appearing as loose clusters) (4)
4 (3) Spikelet scales entire at the tip, with several nerves in addition to the midvein; leaf blades relatively well developed, the uppermost usually extending past the midpoint of the stem 13 Schoenoplectus torreyi
+ Spikelet scales with a small notch at the tip, with only the midvein visible; leaf blades relatively reduced, the uppermost usually not extending as far as the midpoint of the stem (5)
5 (4) Inflorescence bract 1, 1–6 cm long; stems strongly triangular in cross-section, the sides usually noticeably concave when fresh (difficult to see when pressed) 2 Schoenoplectus americanus
+ Inflorescence with 1–2 much-reduced bracts in addition to the main bract, this (1–)5–20 cm long; stems strongly triangular in cross-section, but the sides mostly flat or at most slightly concave when fresh (6)
6 (5) Spikelets 4–35 per inflorescence; perianth bristles mostly longer than the fruits, delicate and often bent or contorted; fruits 1.9–2.6 mm, mostly less than 2.5 mm long 3 Schoenoplectus deltarum
+ Spikelets 1–4(–10) per inflorescence; perianth bristles as long as or shorter than the fruits, relatively stout and straight or slightly arched around the fruit; fruits 2.2–3.3 mm, mostly more than 2.5 mm long 8 Schoenoplectus pungens
7 (1) Inflorescences with numerous spikelets, most or all of these stalked and/or in stalked clusters (the branches rarely relatively short, but noticeable, and the inflorescence thus congested) (8)
+ Inflorescences with 1 spikelet or the 2–10(–15) spikelets all sessile in a headlike cluster (occasionally with 1–2 short-stalked clusters) (10)
8 (7) Fruits 3-angled; spikelets all stalked or rarely a few, stalked clusters of 2 spikelets present 6 Schoenoplectus heterochaetus
+ Fruits unequally biconvex in cross-section (1 side rounded, the other nearly flat); spikelets mostly sessile in stalked clusters of 3–7 (9)
9 (8) Spikelet scales (3–)3.5–4.0 mm long, pale grayish brown with prominent reddish purple spots and/or short lines (visible under magnification); midrib noticeably extended past the main body of the scale 0.5–2.0 mm, mostly bent or contorted; fruits 2.2–2.6 mm long 1 Schoenoplectus acutus
+ Spikelet scales 2–3(–3.5) mm long, orangish brown to dark brown, the reddish purple spots and/or short lines (visible under magnification) often present, but less prominent; midrib less noticeably extended past the main body of the scale 0.2–0.8 mm, straight or sometimes somewhat bent; fruits 1.5–2.3 mm long 12 Schoenoplectus tabernaemontani
10 (7) Plants perennial with delicate, long-creeping rhizomes; fruits 2.5–3.8 mm long 11 Schoenoplectus subterminalis
+ Plants annual or apparently so, the rhizomes, if present, short and hidden by the tufted stem bases; fruits 1.3–2.0 mm long (11)
11 (10) Stigmas 3; fruits 3-angled 10 Schoenoplectus saximontanus
+ Stigmas of florets in main inflorescence 2 (spikelets hidden at stem bases may have 3 stigmas); fruits unequally biconvex (1 side more rounded than the other) (12)
12 (11) Perianth bristles absent; fruits very unequally biconvex (nearly flat on 1 side), broadly rounded on the other, the surface with fine cross-wrinkles 5 Schoenoplectus hallii
+ Perianth bristles 3–6; fruits plump, nearly equally biconvex (both sides broadly rounded), the surface nearly smooth to finely pitted 9 Schoenoplectus purshianus
 
 
 
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