OregonFlora: Eleocharis uniglumis vs. Eleocharis parishii

	Eleocharis palustris (synonym of Eleocharis uniglumis)	Eleocharis parishii
	common spikerush, creeping spikerush, marsh spikerush	Parish'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, mat-forming; rhizomes evident, long, 0.5–1(2) mm thick, cortex persistent, longer internodes 5–30 mm.
Culms	terete or slightly compressed, 30–115 cm × 0.5–5 mm.	terete or cross section elliptic (or rectangular), 10–50 cm × 0.2–0.7(1) 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.	narrowly lanceoloid, 3–20 × 1.5–2.5 mm; proximal scale amplexicaul; entire, subproximal scale empty or with flower; floral scales 15–40, 3–4 per mm of rachilla, 2–3 × 1 mm; apex entire, rounded to obtuse in proximal part of spike; acute in distal part, keeled; at least 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 (0)3–7, often unequal; rudimentary to slightly exceeding tubercle; anthers 1.1–2 mm; stigmas 3.
Achenes	biconvex, 1.1–2 × 1–1.5 mm.	compressed-trigonous, 0.8–1.4 × 0.5–0.7 mm.
Distal leaf sheaths	persistent or sometimes disintegrating, often splitting adaxially; apex lacking tooth.	persistent, not splitting; apex with tooth often present on most or all culms; to 1 mm.
Tubercles	pyramidal to mammillate; as high as wide to 2 times higher, 0.3–0.7 × 0.35–0.7 mm.	pyramidal, often higher than wide, 0.3–0.4 × 0.25–0.35 mm.
2n	=16, 27, 36.	=10.

	Eleocharis palustris	Eleocharis parishii
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.	Fresh to brackish wetlands, often on drying lake shores, pond margins, streamsides and springs. 200–500 m. Sisk. CA, NV; east to Kansas, south to Mexico. Native.
Source	Flora of Oregon, volume 1, page 242 Barbara Wilson, Richard Brainerd, Nick Otting	Flora of Oregon, volume 1, page 242 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. bolanderi, E. decumbens, E. engelmannii, E. erythropoda, E. macrostachya, E. obtusa, E. ovata, E. palustris, 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 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 parishii

common spikerush, creeping spikerush, marsh spikerush

Parish'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, mat-forming; rhizomes evident, long, 0.5–1(2) mm thick, cortex persistent, longer internodes 5–30 mm.

Culms

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

terete or cross section elliptic (or rectangular), 10–50 cm × 0.2–0.7(1) 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.

narrowly lanceoloid, 3–20 × 1.5–2.5 mm;

proximal scale amplexicaul; entire, subproximal scale empty or with flower; floral scales 15–40, 3–4 per mm of rachilla, 2–3 × 1 mm;

apex entire, rounded to obtuse in proximal part of spike; acute in distal part, keeled; at least 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 (0)3–7, often unequal; rudimentary to slightly exceeding tubercle;

anthers 1.1–2 mm;

stigmas 3.

Achenes

biconvex, 1.1–2 × 1–1.5 mm.

compressed-trigonous, 0.8–1.4 × 0.5–0.7 mm.

Distal leaf sheaths

persistent or sometimes disintegrating, often splitting adaxially;

apex lacking tooth.

persistent, not splitting;

apex with tooth often present on most or all culms; to 1 mm.

Tubercles

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

pyramidal, often higher than wide, 0.3–0.4 × 0.25–0.35 mm.

=16, 27, 36.

=10.

Eleocharis parishii

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.

Fresh to brackish wetlands, often on drying lake shores, pond margins, streamsides and springs. 200–500 m. Sisk. CA, NV; east to Kansas, south to Mexico. Native.

Source

Flora of Oregon, volume 1, page 242
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa