Burke: Eleocharis acicularis vs. Eleocharis ambigens

	Eleocharis acicularis	Eleocharis ambigens
	needle spikerush
Habit	Very slender perennial from slender, branching rhizomes, forming dense tufts; culms filiform, 3-12 cm. tall, the basal sheaths pale or purplish.
Leaves	Leaves all basal and reduced to sheaths.
Flowers	Spikelet solitary and terminal, 2.5-7 mm. long, 3- to 15-flowered; scales of the spikelets spirally arranged, 1.5-2.2 mm. long, translucent, with a greenish midrib and paler margins; perianth of 3-4 bristles, equaling the achene, or wanting; stamens 3; style trifid, thickened at the base.
Fruits	Achenes white to pale gray, 0.7-1.1 mm. long, with a conic tubercle (the thickened base of the style), the body obovoid, longitudinally 8- to 18-ribbed.

	Eleocharis acicularis	Eleocharis ambigens
Flowering time	June-September
Habitat	Marshes, muddy shores, and other wet places.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast; circumboreal. [WildflowerSearch map] [BONAP county map]
Origin	Native
Conservation status	Not of concern
Sibling taxa	E. bella, E. bolanderi, E. coloradoensis, E. engelmannii, E. erythropoda, E. geniculata, E. macrostachya, E. mamillata, E. obtusa, E. ovata, E. palustris, E. parvula, E. quinqueflora, E. rostellata, E. suksdorfiana, E. uniglumis	E. acicularis, E. bella, E. bolanderi, E. coloradoensis, E. engelmannii, E. erythropoda, E. geniculata, E. macrostachya, E. mamillata, E. obtusa, E. ovata, E. palustris, E. parvula, E. quinqueflora, E. rostellata, E. suksdorfiana, E. uniglumis
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 acicularis

Eleocharis ambigens

needle spikerush

Habit

Very slender perennial from slender, branching rhizomes, forming dense tufts; culms filiform, 3-12 cm. tall, the basal sheaths pale or purplish.

Leaves

Leaves all basal and reduced to sheaths.

Flowers

Spikelet solitary and terminal, 2.5-7 mm. long, 3- to 15-flowered;

scales of the spikelets spirally arranged, 1.5-2.2 mm. long, translucent, with a greenish midrib and paler margins;

perianth of 3-4 bristles, equaling the achene, or wanting;

stamens 3;

style trifid, thickened at the base.

Fruits

Achenes white to pale gray, 0.7-1.1 mm. long, with a conic tubercle (the thickened base of the style), the body obovoid, longitudinally 8- to 18-ribbed.