OregonFlora: Eleocharis uniglumis vs. Eleocharis bolanderi

	Eleocharis palustris (synonym of Eleocharis uniglumis)	Eleocharis bolanderi
	common spikerush, creeping spikerush, marsh spikerush	Bolander's spikerush
Habit	Plants perennial, mat-forming; rhizomes evident, long, 1.5–4.5 mm thick, cortex persistent, longer internodes 10–35 mm.	Plants perennial, densely cespitose; rhizomes caudex-like, mostly hidden by culms and roots, short, 1.5–3 mm thick, internodes very short.
Culms	terete or slightly compressed, 30–115 cm × 0.5–5 mm.	subterete, 10–30 cm × 0.3–0.5 mm.
Spikes	ovoid to lanceoloid, 5–25 × 3–7 mm; proximal scale clasping 67(75)% of culm, subproximal scales 1–2; empty; floral scales 30–100, 4–8 per mm of rachilla, 3–5 × 1.5–2.5 mm; apex entire; acute or subacute, often keeled in distal part of spike.	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 4(5), sometimes absent; much shorter than achene to equaling tubercle, rarely to 2 times as long as achene; anthers 1.5–2.2 mm; stigmas 2; very rarely some 3.	perianth bristles 3–6, often unequal; from rudimentary to 50% of achene length; anthers 0.9–1.4 mm; stigmas 3.
Achenes	biconvex, 1.1–2 × 1–1.5 mm.	slightly to greatly compressed-trigonous, rarely thickly lenticular, 0.9–1.2 × 0.65–0.8 mm.
Distal leaf sheaths	persistent or sometimes disintegrating, often splitting adaxially; apex lacking tooth.	persistent, not splitting; apex obtuse, rarely hardened, lacking a tooth.
Tubercles	pyramidal to mammillate; as high as wide to 2 times higher, 0.3–0.7 × 0.35–0.7 mm.	flat to shallowly pyramidal; lower than wide, 0.1–0.3 × 0.4–0.65 mm.
2n	=16, 27, 36.

	Eleocharis palustris	Eleocharis bolanderi
Distribution	[WildflowerSearch map]	[WildflowerSearch map] [BONAP county map]
Discussion	Freshwater marshes, lake shores, streamsides, and ponds. 0–2300 m. All ecoregions except Col. CA, ID, NV, WA; north to AK, east to Newfoundland, south to Mexico; Eurasia, New Zealand. Native. Eleocharis palustris is the most common species in a taxonomically difficult, circumboreal complex of the genus. Its pure, rhizomatous stands can dominate plant communities in shallow wetlands. It can usually be recognized by its subequal proximal and subproximal scales, both lacking flowers. Culm widths overlap those of E. macrostachya, but the very widest spikerush culms in Oregon belong to E. palustris.	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 242 Barbara Wilson, Richard Brainerd, Nick Otting	Flora of Oregon, volume 1, page 240 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	E. acicularis, E. bella, E. bolanderi, 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. 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
Synonyms	Eleocharis mamillata, Eleocharis palustris var. major, Eleocharis palustris var. palustris, Eleocharis uniglumis
Web links	Local floras: BC, OR, WA Local Web sites: 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: 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 bolanderi

common spikerush, creeping spikerush, marsh spikerush

Bolander's spikerush

Habit

Plants perennial, mat-forming; rhizomes evident, long, 1.5–4.5 mm thick, cortex persistent, longer internodes 10–35 mm.

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

Culms

terete or slightly compressed, 30–115 cm × 0.5–5 mm.

subterete, 10–30 cm × 0.3–0.5 mm.

Spikes

ovoid to lanceoloid, 5–25 × 3–7 mm;

proximal scale clasping 67(75)% of culm, subproximal scales 1–2; empty; floral scales 30–100, 4–8 per mm of rachilla, 3–5 × 1.5–2.5 mm;

apex entire; acute or subacute, often keeled in distal part of spike.

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 4(5), sometimes absent; much shorter than achene to equaling tubercle, rarely to 2 times as long as achene;

anthers 1.5–2.2 mm;

stigmas 2; very rarely some 3.

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

anthers 0.9–1.4 mm;

stigmas 3.

Achenes

biconvex, 1.1–2 × 1–1.5 mm.

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

Distal leaf sheaths

persistent or sometimes disintegrating, often splitting adaxially;

apex lacking tooth.

persistent, not splitting;

apex obtuse, rarely hardened, lacking a tooth.

Tubercles

pyramidal to mammillate; as high as wide to 2 times higher, 0.3–0.7 × 0.35–0.7 mm.

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

=16, 27, 36.

Eleocharis bolanderi

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Freshwater marshes, lake shores, streamsides, and ponds. 0–2300 m. All ecoregions except Col. CA, ID, NV, WA; north to AK, east to Newfoundland, south to Mexico; Eurasia, New Zealand. Native.

Eleocharis palustris is the most common species in a taxonomically difficult, circumboreal complex of the genus. Its pure, rhizomatous stands can dominate plant communities in shallow wetlands. It can usually be recognized by its subequal proximal and subproximal scales, both lacking flowers. Culm widths overlap those of E. macrostachya, but the very widest spikerush culms in Oregon belong to E. palustris.

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 242
Barbara Wilson, Richard Brainerd, Nick Otting

Flora of Oregon, volume 1, page 240
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa