OregonFlora: Eleocharis bolanderi vs. Eleocharis macrostachya

	Eleocharis bolanderi	Eleocharis macrostachya
	Bolander's spikerush	confusing spikerush, pale spikerush
Habit	Plants perennial, densely cespitose; rhizomes caudex-like, mostly hidden by culms and roots, short, 1.5–3 mm thick, internodes very short.	Plants perennial; rhizomes evident, long, 1–2 mm thick, firm, cortex persistent, longer internodes 10–55 mm.
Culms	subterete, 10–30 cm × 0.3–0.5 mm.	terete to markedly compressed; to 3 times wider than thick, 10–100 cm × 0.5–2.5(3.5) mm.
Spikes	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.	narrowly lanceoloid to ovoid, 5–40 × 2–5 mm; proximal scale clasping (6)75(100)% of culm usually variably in same plant, subproximal scale usually empty in some spikes and subtending a flower in other spikes in the same clone; floral scales 30–80, 3–5 per mm of rachilla, 2.5–5.5 × 1.5–2.5 mm.
Flowers	perianth bristles 3–6, often unequal; from rudimentary to 50% of achene length; anthers 0.9–1.4 mm; stigmas 3.	perianth bristles 4(5), sometimes rudimentary or absent; much shorter than achene to equaling tubercle; stamens 2(3); anthers 1.3–2.7 mm; stigmas 2.
Achenes	slightly to greatly compressed-trigonous, rarely thickly lenticular, 0.9–1.2 × 0.65–0.8 mm.	biconvex to plano-convex, 1.1–1.9 × 0.8–1.5 mm.
Distal leaf sheaths	persistent, not splitting; apex obtuse, rarely hardened, lacking a tooth.	persistent; apex truncate to obtuse; tooth sometimes present on some or all culms, 0.1–0.6(1) mm.
Tubercles	flat to shallowly pyramidal; lower than wide, 0.1–0.3 × 0.4–0.65 mm.	pyramidal; as high as or sometimes much higher than wide, 0.35–0.7 × 0.25–0.7 mm.
2n		=18, 19, 38.

	Eleocharis bolanderi	Eleocharis macrostachya
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map]
Discussion	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.	Fresh to slightly brackish or alkaline marshes, lake shores, stream beds, vernal pools, deflation plains, and wet meadows. 0–1800 m. BR, BW, Col, CR, ECas, Est, Lava, Owy, Sisk, WV. CA, ID, NV, WA; north to AK, east to Quebec and MS, south to Mexico; South America. Native. Eleocharis macrostachya is a diploid-polyploid complex consisting (at least in part) of populations that originated as hybrids of E. palustris with E. erythropoda and E. uniglumis. As a result, E. macrostachya is one of the most variable species in the genus. Plants vary from short, narrow-culmed plants resembling E. erythropoda to fairly robust individuals resembling E. palustris. The extent to which the proximal scale clasps the culm is usually greater than in E. palustris and often varies within a clone, as does the present or absence of a flower in the subproximal scale. Strictly coastal individuals have shiny dark chestnut brown or blackish achenes with brownish midribs. The proximal scales usually clasp 95–100% of the culm, and the subproximal scales usually subtend flowers. The culms are tough and sometimes arching. These plants can be referred to as E. macrostachya variant C (coastal form) or E. macrostachya tending toward E. uniglumis, according to Smith et al. (2002). Most inland Oregon plants are referred to as E. m. variant B.
Source	Flora of Oregon, volume 1, page 240 Barbara Wilson, Richard Brainerd, Nick Otting	Flora of Oregon, volume 1, page 241 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	E. acicularis, E. bella, E. decumbens, E. engelmannii, E. erythropoda, E. macrostachya, E. obtusa, E. ovata, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. rostellata, E. suksdorfiana	E. acicularis, E. bella, E. bolanderi, E. decumbens, E. engelmannii, E. erythropoda, E. obtusa, E. ovata, E. palustris, E. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. rostellata, E. suksdorfiana
Web links	Local floras: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Eleocharis macrostachya

Bolander's spikerush

confusing spikerush, pale spikerush

Habit

Plants perennial, densely cespitose; rhizomes caudex-like, mostly hidden by culms and roots, short, 1.5–3 mm thick, internodes very short.

Plants perennial; rhizomes evident, long, 1–2 mm thick, firm, cortex persistent, longer internodes 10–55 mm.

Culms

subterete, 10–30 cm × 0.3–0.5 mm.

terete to markedly compressed; to 3 times wider than thick, 10–100 cm × 0.5–2.5(3.5) mm.

Spikes

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.

narrowly lanceoloid to ovoid, 5–40 × 2–5 mm;

proximal scale clasping (6)75(100)% of culm usually variably in same plant, subproximal scale usually empty in some spikes and subtending a flower in other spikes in the same clone; floral scales 30–80, 3–5 per mm of rachilla, 2.5–5.5 × 1.5–2.5 mm.

Flowers

perianth bristles 3–6, often unequal; from rudimentary to 50% of achene length;

anthers 0.9–1.4 mm;

stigmas 3.

perianth bristles 4(5), sometimes rudimentary or absent; much shorter than achene to equaling tubercle;

stamens 2(3);

anthers 1.3–2.7 mm;

stigmas 2.

Achenes

slightly to greatly compressed-trigonous, rarely thickly lenticular, 0.9–1.2 × 0.65–0.8 mm.

biconvex to plano-convex, 1.1–1.9 × 0.8–1.5 mm.

Distal leaf sheaths

persistent, not splitting;

apex obtuse, rarely hardened, lacking a tooth.

persistent;

apex truncate to obtuse; tooth sometimes present on some or all culms, 0.1–0.6(1) mm.

Tubercles

flat to shallowly pyramidal; lower than wide, 0.1–0.3 × 0.4–0.65 mm.

pyramidal; as high as or sometimes much higher than wide, 0.35–0.7 × 0.25–0.7 mm.

=18, 19, 38.

Eleocharis bolanderi

Eleocharis macrostachya

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

Discussion

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.

Fresh to slightly brackish or alkaline marshes, lake shores, stream beds, vernal pools, deflation plains, and wet meadows. 0–1800 m. BR, BW, Col, CR, ECas, Est, Lava, Owy, Sisk, WV. CA, ID, NV, WA; north to AK, east to Quebec and MS, south to Mexico; South America. Native.

Eleocharis macrostachya is a diploid-polyploid complex consisting (at least in part) of populations that originated as hybrids of E. palustris with E. erythropoda and E. uniglumis. As a result, E. macrostachya is one of the most variable species in the genus. Plants vary from short, narrow-culmed plants resembling E. erythropoda to fairly robust individuals resembling E. palustris. The extent to which the proximal scale clasps the culm is usually greater than in E. palustris and often varies within a clone, as does the present or absence of a flower in the subproximal scale. Strictly coastal individuals have shiny dark chestnut brown or blackish achenes with brownish midribs. The proximal scales usually clasp 95–100% of the culm, and the subproximal scales usually subtend flowers. The culms are tough and sometimes arching. These plants can be referred to as E. macrostachya variant C (coastal form) or E. macrostachya tending toward E. uniglumis, according to Smith et al. (2002). Most inland Oregon plants are referred to as E. m. variant B.