Eleocharis engelmannii |
Eleocharis wolfii |
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Engelman spikerush, Engelmann's spike-rush, Engelmann's spikesedge, englemann's spike-rush |
Wolf's spike-rush |
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Habit | Plants perennial, often forming large mats; rhizomes 0.25–0.6 mm thick, internodes 1–4 cm, scales 2 mm. | |
Culms | 2–40 cm × 0.5–1.5(–2) mm. |
sometimes decumbent, in same plant sides variably smooth or with 1 to few acute ridges (often nearly smooth or with 1 ridge on 1 side and several ridges on the other), greatly compressed, usually inrolled when dry, rectangular in cross section, 10–40 cm × 0.3–1.5 mm, 0.2–0.5 mm thick, firm, margins often sharply acute, margins and often 1 or more ridges minutely serrulate at 20–30X. |
Leaves | apex of distal leaf sheath obtuse to acute, tooth to 0.3 mm. |
distal leaf sheaths persistent, red proximally, colorless or stramineous or whitish distally, slightly inflated, thickly membranous, apex acute. |
Spikelets | lanceoloid to subcylindric or ovoid, 5–10(–20) × 2–3(–4) mm, apex acute (to rounded); proximal scale empty, encircling ca. 2/3 of culm; floral scales 25–100(–200), 8–12 per mm of rachilla, orangebrown to stramineous, 2(–2.5) × 1–1.3 mm, midribs mostly keeled, ovate, apex narrowly rounded to subacute. |
ovoid or lanceoloid, 3–9 × 1.5–2.5 mm, apex acute; floral scales 15–30, 6 per mm of rachilla, orange-brown or often stramineous or colorless, midrib region stramineous or greenish, ovate-lanceolate, (2.2–)2.7–3.2 × 1.5 mm, midrib prominent, apex acute. |
Flowers | perianth bristles present or often absent, 5–8, brown, stout, rudimentary to slightly exceeding tubercle; stamens (2–)3; anthers brown to yellow, 0.3–0.7(–1) mm; styles 2–3-fid. |
perianth bristles absent; anthers 1.1–1.75 mm. |
Achenes | 0.9–1.1(–1.5) × 0.7–1.1 mm. |
compressed-trigonous, with angles plus longitudinal ridges ca. 9–13, prominent, obovoid, mostly 2 times longer than wide, 0.7–0.9(–1.1) × (0.4–)0.5 mm, trabeculae 30–60, rather obscure and crowded. |
Tubercles | depressed, subdeltoid, 0.1–0.3(–0.4) × 0.6–0.9(–1) mm, 1/10–2/5 as high as wide, 1/4 or less as high as achene, 9/10 as wide as achene, very rarely 2/5 as high as achene (in E. engelmannii var. robusta). |
brownish, pyramidal, usually depressed, 0.1–0.15 × 0.2–0.25 mm. |
2n | = 10. |
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Eleocharis engelmannii |
Eleocharis wolfii |
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Phenology | Fruiting spring–fall. | Fruiting late spring–early summer (May–Jun). |
Habitat | Fresh shores, marshes, disturbed places | Ephemeral pools in open grasslands, oak woodlands on river terraces, limestone barrens |
Elevation | 30–2400 m (100–7900 ft) | 10–500 m (0–1600 ft) |
Distribution |
AL; AR; AZ; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; KY; MA; MD; MI; MN; MO; MS; MT; ND; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; TN; TX; VA; WA; WI; WV; AB; BC; MB; ON
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AL; AR; CO; IA; IL; IN; KS; LA; MN; MO; MS; ND; NY; OH; OK; TN; TX; WI
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Discussion | Robust plants known only from Missouri and described as Eleocharis engelmannii var. robusta have well-developed caudices, culms to 2 mm wide (pressed), spikelets to 2 cm, floral scales to 2.5 mm and slightly cartilaginous, styles mostly trifid, achenes to 1.5 × 1 mm, and tubercles 0.3–0.5 × 0.7–1 mm and to 2/5 as high as achene. Some specimens are intermediate between E. engelmannii and E. obtusa, or rarely with E. lanceolata. I have not seen specimens to verify literature reports of E. engelmannii from Manitoba, Connecticut, Delaware, Idaho, New Hampshire, North Carolina, Oregon, Rhode Island, South Carolina, South Dakota, or Vermont. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eleocharis wolfii is presumably extirpated from Colorado, Kansas, New York (Long Island), and Ohio. It was recently rediscovered in Wisconsin. Some literature reports (e.g. from the Great Plains) are based on misidentified specimens. I have not seen specimens to verify literature reports from Alberta, Saskatchewan, Colorado, Missouri, and Nebraska. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 104. | FNA vol. 23, p. 110. |
Parent taxa | Cyperaceae > Eleocharis > subg. Eleocharis > sect. Eleogenus > ser. Ovatae | Cyperaceae > Eleocharis > subg. Scirpidium |
Sibling taxa | ||
Synonyms | E. engelmannii var. detonsa, E. engelmannii var. monticola, E. engelmannii var. robusta, E. monticola, E. monticola var. leviseta, E. ovata var. detonsa | Scirpus wolfii |
Name authority | Steudel: Syn. Pl. Glumac. 2: 79. (1855) | (A. Gray) A. Gray ex Britton: in H. N. Patterson, Cat. Pl. Illinois, 46. (1876) |
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