OregonFlora: Eleocharis baldwinii vs. Eleocharis decumbens

	Eleocharis baldwinii	Eleocharis decumbens
		decumbent spikerush
Habit		Plants perennial, densely tufted; rhizomes often hidden by the crowded culms and roots, 3–4 mm thick, hard, longer internodes from very short to 5 mm; rhizome scales usually clearly evident, 2–2.5 cm, papery and disintegrating to fibers.
Culms		terete 10–50 cm × 0.3–2 mm.
Spikes		ovoid, 3–8 × 2–2.5 mm; apex acute; proximal scale amplexicaul, subproximal scale empty or with flower; floral scales 10–20, 3–3.5 × 1.5 mm; apex acute.
Flowers		perianth bristles 6, mostly equaling or exceeding tubercle; (0.5)1–2.2 mm; anthers 1.2–1.5 mm; stigmas 3.
Achenes		nearly equilaterally- to greatly compressed-trigonous, 1–1.3 × 0.75–0.9 mm; neck absent or short.
Distal leaf sheaths		persistent, lacking a tooth.
Tubercles		well developed; pyramidal; as wide as high to much wider than high, 0.2–0.6 × 0.4–0.7 mm.

	Eleocharis baldwinii	Eleocharis decumbens
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion		Fens, seeps, and lake shores, montane to alpine. 1500–1700 m. Casc. CA. Native. Eleocharis decumbens is most easily identified by the crowded, 2 cm or longer scales on its thick rhizomes. It occurs with E. suksdorfiana in montane wetlands in southwestern Oregon.
Source		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. bolanderi, 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 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 baldwinii

Eleocharis decumbens

decumbent spikerush

Habit

Plants perennial, densely tufted; rhizomes often hidden by the crowded culms and roots, 3–4 mm thick, hard, longer internodes from very short to 5 mm; rhizome scales usually clearly evident, 2–2.5 cm, papery and disintegrating to fibers.

Culms

terete 10–50 cm × 0.3–2 mm.

Spikes

ovoid, 3–8 × 2–2.5 mm;

apex acute;

proximal scale amplexicaul, subproximal scale empty or with flower; floral scales 10–20, 3–3.5 × 1.5 mm;

apex acute.

Flowers

perianth bristles 6, mostly equaling or exceeding tubercle; (0.5)1–2.2 mm;

anthers 1.2–1.5 mm;

stigmas 3.

Achenes

nearly equilaterally- to greatly compressed-trigonous, 1–1.3 × 0.75–0.9 mm; neck absent or short.

Distal leaf sheaths

persistent, lacking a tooth.

Tubercles

well developed; pyramidal; as wide as high to much wider than high, 0.2–0.6 × 0.4–0.7 mm.

Eleocharis baldwinii

Eleocharis decumbens

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Fens, seeps, and lake shores, montane to alpine. 1500–1700 m. Casc. CA. Native.

Eleocharis decumbens is most easily identified by the crowded, 2 cm or longer scales on its thick rhizomes. It occurs with E. suksdorfiana in montane wetlands in southwestern Oregon.

Source

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

Sibling taxa