OregonFlora: Eleocharis ovata vs. Eleocharis bifida

	Eleocharis ovata	Eleocharis bifida
	ovoid spikerush
Habit	Plants annual, tufted.
Culms	terete, 2–35 cm × 0.3–1 mm.
Spikes	ovoid, 2–8 × 2–4 mm; floral scales 25–100+, approximately 10 per mm of rachilla, 1.5–2 × 1 mm; midribs often keeled in distal part of spike; apex rounded to subacute.
Flowers	perianth bristles present, rarely absent; (5)6–7, exceeding tubercle; stamens 2(3); anthers 0.3 mm; stigmas 2 or some 3.
Achenes	biconvex or to 33% greatly compressed trigonous, 0.75–1 × 0.6–0.85 mm.
Distal leaf sheaths	persistent, apex of distal leaf sheath obtuse to acute; tooth to 0.2 mm.
Tubercles	deltoid, 0.3–0.5 × 0.3–0.5 mm, 60% to as high as wide, 33–67% as high and 50–75% as wide as achene.
2n	=10.

	Eleocharis ovata	Eleocharis bifida
Distribution	[WildflowerSearch map]	[BONAP county map]
Discussion	Freshwater shores exposed by seasonal low water levels, marshes, and disturbed wetlands. 100–1300 m. ECas, Sisk, WV. WA; north to British Columbia; northeastern North America. Native? Pacific Northwest occurrences of E. ovata are disjunct from the species northeastern North American range. This may suggest that the species is introduced in Oregon. More research is needed.
Source	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. 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. parishii, E. parvula, E. quadrangulata, E. quinqueflora, E. rostellata, E. suksdorfiana
Web links	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	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

Eleocharis ovata

Eleocharis bifida

ovoid spikerush

Habit

Plants annual, tufted.

Culms

terete, 2–35 cm × 0.3–1 mm.

Spikes

ovoid, 2–8 × 2–4 mm; floral scales 25–100+, approximately 10 per mm of rachilla, 1.5–2 × 1 mm; midribs often keeled in distal part of spike;

apex rounded to subacute.

Flowers

perianth bristles present, rarely absent; (5)6–7, exceeding tubercle;

stamens 2(3);

anthers 0.3 mm;

stigmas 2 or some 3.

Achenes

biconvex or to 33% greatly compressed trigonous, 0.75–1 × 0.6–0.85 mm.

Distal leaf sheaths

persistent, apex of distal leaf sheath obtuse to acute; tooth to 0.2 mm.

Tubercles

deltoid, 0.3–0.5 × 0.3–0.5 mm, 60% to as high as wide, 33–67% as high and 50–75% as wide as achene.

=10.

Eleocharis ovata

Eleocharis bifida

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Freshwater shores exposed by seasonal low water levels, marshes, and disturbed wetlands. 100–1300 m. ECas, Sisk, WV. WA; north to British Columbia; northeastern North America. Native?

Pacific Northwest occurrences of E. ovata are disjunct from the species northeastern North American range. This may suggest that the species is introduced in Oregon. More research is needed.

Source

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

Sibling taxa