Cyperus echinatus
Cyperus fugax
globe flatsedge, teasel sedge
withering flatsedge
basally cormlike, trigonous, (15–)30–100 cm × 0.5–3.5 mm, glabrous.
(1–)10–30(–60) together, roundly trigonous proximally, trigonous distally, (0.5–)3–6(–12) cm × (0.2–)0.4–0.8 mm, glabrous.
flat to V-shaped, 10–65 cm × 3–9 mm, adaxial surface, margins minutely scabridulous.
V-shaped, (1–)3–5(–10) cm × (0.5–)1–2 mm.
spikes densely globose to globose-ovoid, 8–17 mm wide;
rays 3–12, 2–12 cm, scaberous adaxially especially distally;
rachis 4–8 mm;
bracts (3–)4–7, ascending at 30(–45)°, flat, 5–35 cm × 2–9 mm;
rachilla persistent, wings 0.5–0.7 mm wide.
spikes loosely ovoid, 8–15(–25) mm wide;
rachis 1–3 mm;
rays (1–)2–4(–6), (0.5–)1–3(–6) cm; 2d order rays absent;
bracts (1–)2–4(–5), ascending at 30–45°, V-shaped, (1–)2.5–6(–11) cm × 0.5–1.8 mm.
50–100, oblong-lanceoloid, ± terete-quadrangular, (3.5–)4–7 × 1–1.4 mm;
distal spikelet spreading or ascending;
floral scales persistent, 3–5, appressed, stramineous to brownish, 4-ribbed laterally, oblong-elliptic, 3.5–4.5 × 1–1.8 mm, membranous, apex entire or emarginate with mucro to 0.3 mm.
(2–)4–6(–10), linear-lanceoloid, strongly flattened, (5–)8–12(–18) × 1.2–1.5 (1.8) mm;
floral scales (5–)10–16(–32), laterally clear, stramineous or light reddish brown, medially green, laterally ribless, medially 3(–5)-ribbed, ovate, (1.2–)1.3–1.6(–2) × 1–1.2(–1.4) mm, apex obtuse, mucronate to minutely mucronulate.
anthers 0.4–0.8 mm;
styles 0.5–0.6 mm;
stigmas 1 mm.
stamens 2;
anthers 0.1–0.2 mm;
styles 0.1–0.3(–0.4) mm;
stigmas 0.3–0.4 mm.
brown, ± stipitate, oblong, (1.5–)1.8–2.3 × 0.5–0.6(–0.7) mm (1/2 length of floral scales), apex obtuse, surfaces puncticulate.
light to dark brown, glossy or iridescent, stipitate, oblong-obovoid, 0.9–1.1 × 0.4–0.5 mm, stipe 0.1 mm, apex truncate, apiculate, surfaces punctate.
Cyperus echinatus
Cyperus fugax
The records for Rhode Island and Wisconsin are according to M. L. Horvat (1941); we have not seen specimens from those states.
Cyperus echinatus is usually recognized by its tight, nearly spheric spikes; it may occasionally be hard to distinguish from C. croceus and C. retrorsus. Compared to C. retrorsus, C. echinatus has larger spikelets and longer floral scales, anthers, and achenes. In contrast to C. echinatus, C. croceus has looser spikes, shorter, broader, greenish or yellowish floral scales, shorter, more ovoid achenes, and shorter anthers. Furthermore, C. echinatus is predominantly an inland species of roadsides, pastures, and other disturbed ground; C. retrorsus is primarily a coastal species and occurs in drier, sandier sites.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Cyperus fugax is known from Louisiana from an early nineteeth century collection from “western Louisiana” (Hale s.n., TCD).
Cyperus fugax has been treated as a form of C. polystachyos (G. Kükenthal 1935–1936; A. B. Ayers 1946); nevertheless, specific status is appropriate. The most conspicuous differences are the annual habit and small size (less than 12 cm) of C. fugax; C. polystachyos is a perennial of moderate size (mostly taller than 20 cm). Other differences are summarized below.
Cyperus polystachyos is characterized as a shortly rhizomatous perennial; floral scales oblong, 1.8–2.4 mm, closely imbricate; styles 0.6–1 mm; stigmas 1.4–2 mm; anthers 0.6–0.8 mm; achenes substipitate to cuneate, slightly compressed laterally.
Cyperus fugax is characterized as a nonrhizomatous annual; floral scales ovate, 1.3–1.6 mm, loosely imbricate; styles 0.1–0.2 mm; stigmas 0.3–0.4 mm; filaments 1.2–1.4 mm; anthers 0.1–0.2 mm; achenes stipitate, strongly compressed laterally.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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