Cyperus drummondii
Cyperus cephalanthus
Drummond's sedge
buttonbush flatsedge
trigonous, 35–170 cm × 2–4.7 mm, scabrid on angles.
trigonous, 40–70(–100) cm × 2–3 mm, scabrid or hirtellate, either immediately proximal to apex or over distal 1/2 of culm.
4–12, with readily visible cross ribs especially on abaxial surface, flat to V-shaped, 25–100 cm × 2.4–11 mm.
flat, 30–80 cm × 4–10 mm, scabrid on margins, ribs on abaxial surface.
heads digitate, globose, 1–1.7 cm diam.;
rays 3–5, 1–7 cm; 2d order rays absent;
bracts 3–5, horizontal to ascending at 30°, with prominent cross ribs, V-shaped, (4–)11–35(–48) cm × 1–6.7 mm (longest 1/2 as long as culm); 2d order bracts absent.
spikes ovoid, 12–20 × 13–18 mm;
rays 3–6, 4–10(–16) cm, glabrous;
bracts 3–5, ± horizontal to reflexed, 3–12(–36) cm × 0.4–3(–5) mm, scabrid like leaves;
rachilla deciduous, essentially wingless or wings inconspicuous, hyaline, 0.1(–0.2) mm wide.
10–40, oblong to linear-lanceoloid, 5–1.8 × 1.5–2.2 mm;
floral scales 18–42, pale grayish green, turning brownish, proximally greenish or brownish, 2-keeled, weakly to distinctly 1-ribbed, proximal 1/2 2-ribbed, ovate, 1.4–1.6 × 0.9–1.4 mm, acute (sometimes mucronulate), apically glabrous, occasionally scabridulous.
25–50(–80), oblong, quadrangular-compressed, 5–10 × 2.5–3.5 mm;
floral scales deciduous, 4–10(–14), marginally clear, laterally brownish to clear distally, or light brown or reddish brown, blunt, laterally 3(–4)-ribbed, ovate-lanceolate, 2.5–3 × (1.2–)1.4–2 mm, often erose apically, apex acute to obtuse, entire or emarginate.
stamens 1–2;
anthers 0.8–1.2 mm;
styles 0.8–1 mm;
stigmas 0.6–0.8 mm.
anthers 0.4–0.6 mm;
styles 0.8–1.2 mm;
stigmas 2 mm.
brown, slightly stipitate, oblong-ellipsoid (2.4–3.9 times longer than wide), 1–1.2 × 0.3–0.5 mm, apical beak 0.1–0.5 mm, surfaces glabrous.
brown to reddish brown, ± stipitate, ellipsoid, 1.2 × 0.5–0.6 mm, apex obtuse, scarcely to distinctly apiculate, surfaces puncticulate.
Cyperus drummondii
Cyperus cephalanthus
Cyperus drummondii has been treated as a synonym (G. C. Tucker 1994), or a variety (G. Kükenthal 1935–1936), or a subspecies of C. virens (M. F. Denton 1978b). Recent quantitative and field studies (J. R. Carter et al. 1999) provided compelling evidence that specific status is appropriate.
Compared to Cyperus virens, C. drummondii is a taller species of less disturbed habitats and has narrower spikelets, ovate scales, and fewer inflorescence bracts. Cyperus virens and C. drummondii are readily distinguished from other Cyperus species in the United States by their sharply angled, scabrid culms and conspicuously septate leaf blades.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The combination of spreading floral scales and scabrid culms separates this rather uncommon species from any others occurring in its range. The scarcity of Cyperus cephalanthus in the United States and its disjunct distribution suggest it might be naturalized rather than native. It was collected early in the nineteenth century in Louisiana, and the amphitropical distribution is not without parallel in the genus (cf. 12. C. eragrostis).
Cyperus cephalanthus has been treated as a variety of the widespread, polymorphic South American C. laetus (G. Kükenthal 1935–1936). Recognition of C. cephalanthus as a species follows recent American floristic practice.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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