Eleocharis engelmannii |
Eleocharis bolanderi |
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Engelmann's spikerush |
Bolander's spikerush |
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Habit | Plants annual, tufted. | Plants perennial, densely cespitose; rhizomes caudex-like, mostly hidden by culms and roots, short, 1.5–3 mm thick, internodes very short. |
Culms | terete, 2–40 cm × 0.5–1.5(2) mm. |
subterete, 10–30 cm × 0.3–0.5 mm. |
Spikes | lanceoloid to subcylindric, 5–10(20) × 2–3(4) mm; proximal scale empty, encircling approximately 67% of culm; floral scales 25–100(200), 8–12 per mm of rachilla, 2(2.5) × 1–1.3 mm; apex narrowly rounded to subacute. |
ovoid, 3–8 × 2–3 mm; proximal scale clasping; entire, subproximal scale with flower; floral scales 8–30, 4–5 per mm of rachilla, 2–3 × 1.5 mm; apex entire; acute, often keeled in distal part of spike. |
Flowers | perianth bristles present or often absent; (0)5–8; about as long as the achenes; anthers 0.3–0.7(1) mm; stigmas 2–3. |
perianth bristles 3–6, often unequal; from rudimentary to 50% of achene length; anthers 0.9–1.4 mm; stigmas 3. |
Achenes | biconvex or to 33% greatly compressed trigonous, 0.9–1.1(1.5) × 0.7– 1.1 mm. |
slightly to greatly compressed-trigonous, rarely thickly lenticular, 0.9–1.2 × 0.65–0.8 mm. |
Distal leaf sheaths | persistent, apex of distal leaf sheath obtuse to acute, with tooth to 0.3 mm. |
persistent, not splitting; apex obtuse, rarely hardened, lacking a tooth. |
Tubercles | depressed, subdeltoid, 0.1–0.3(0.4) × 0.6–0.9(1) mm, 10–40% as high as wide, 25% or less as high as achene, 90% as wide as achene. |
flat to shallowly pyramidal; lower than wide, 0.1–0.3 × 0.4–0.65 mm. |
Eleocharis engelmannii |
Eleocharis bolanderi |
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Distribution | ||
Discussion | Freshwater shores exposed by seasonal low water levels, marshes, disturbed wetlands. 50–500 m. WV. CA, ID, WA; north to British Columbia, east to MA, southeast to AL. Native. Eleocharis engelmannii is similar to E. ovata and the much more common E. obtusa but has markedly shorter tubercles and usually more cylindric spikes. |
Shallow, rocky, ephemeral streams. 1100–2100 m. BR, BW, Owy. CA, NV, ID; east to CO. Native. Eleocharis bolanderi is easily recognized in summer when it forms masses of dry, brown, dormant and apparently dead culms in dry stream beds. It is easily pulled up to expose its cespitose habit. The virtually flat tubercles are particularly distinctive. |
Source | Flora of Oregon, volume 1, page 241 Barbara Wilson, Richard Brainerd, Nick Otting |
Flora of Oregon, volume 1, page 240 Barbara Wilson, Richard Brainerd, Nick Otting |
Sibling taxa | ||
Synonyms | Eleocharis engelmannii var. engelmannii, Eleocharis engelmannii var. monticola, Eleocharis obtusa var. engelmannii | |
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