Eleocharis melanocarpa |
Eleocharis acicularis |
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needle spikerush |
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Habit | Plants perennial; rhizomes 0.25–0.5 mm thick, internodes 5–15 mm, sometimes with resting buds. | |
Culms | sometimes arching; terete to sometimes distinctly compressed, 1–60 cm × 0.2–0.5(0.7) mm. |
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Spikes | 2–8 × 1–2 mm; floral scales 4–25, 4–6 per mm of rachilla, 1.5–2.5(3.5) × 1–1.5 mm; apex blunt to acute. |
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Flowers | perianth bristles mostly absent, uncommonly 2–4; shorter than to equaling achene; anthers 0.7–1.5 mm; stigmas 3. |
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Achenes | with angles plus about 8–12 obscure to prominent longitudinal ridges, narrowly to broadly obovoid to obpyriform, 0.7–1.1 × 0.35–0.6 mm; fine horizontal ridges 30–60, clearly evident to crowded and obscure; spaces between trabeculae sometimes translucent. |
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Distal leaf sheaths | often splitting; apex rounded (to acute). |
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Tubercles | pyramidal to much depressed; (0.05)0.1–0.2 × 0.15– 0.25 mm. |
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2n | =20. |
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Eleocharis melanocarpa |
Eleocharis acicularis |
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Distribution | ||
Discussion | Ponds, shallow wetlands, and exposed shorelines and mudflats, vernal pools, and other, often disturbed wetlands. 0–2300 m. All ecoregions except Col. CA, ID, NV, WA; north to AK, east to Greenland and GA, south to South America; Australia, Eurasia. Native. Plants of this species frequently grow as submerged or floating mats that do not flower. These plants differ from typical E. acicularis in having terete, smooth, soft, translucent culms with conspicuous partitions between the air cavities. Such plants are difficult to identify and can be confused with Schoenoplectus subterminalis. Eleocharis acicularis is highly variable, but much of the variation is probably environmental, dependent particularly on water depth. As a result of this plasticity, recognition of any of the described varieties is likely unwarranted. Eleocharis bella is similar but annual, cespitose, only occasionally produces rhizomes and has smaller floral scales, anthers, and achenes. |
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Source | Flora of Oregon, volume 1, page 240 Barbara Wilson, Richard Brainerd, Nick Otting |
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Sibling taxa | ||
Synonyms | Eleocharis acicularis var. acicularis, Eleocharis acicularis var. occidentalis | |
Web links |
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