OregonFlora: Eleocharis quadrangulata vs. Eleocharis baldwinii

	Eleocharis quadrangulata	Eleocharis baldwinii
	four-angled spikerush, square-stemmed spikerush
Habit	Plants perennial; rhizomes 1.5–4 mm thick, longer internodes 3–8 cm, tubers absent.
Culms	acutely quadrangular; (30)45–105 cm × (1)2–5.4 mm.
Spikes	(15)20–76 × 3–5(6) mm; proximal scale empty; amplexicaul; (1)2.2–5.4 mm; floral scales (28)45–135, 2–3 per mm of rachilla; (4)4.5–6.2 × 2.8–5 mm; apex rounded to obtuse.
Flowers	perianth bristles 6–7, often markedly unequal; shorter than achene or some equaling tubercle; anthers 2.3–2.9 mm; stigmas 3, sometimes 2.
Achenes	biconvex, 1.8–3 × 1.3–2 mm; almost smooth to markedly sculptured at 10–15×; each face with 19–38 rows of almost linear, transversely elongated cells; which are sometimes isodiametric at achene base.
Distal leaf sheaths	persistent; apex narrowly acute to acuminate, sometimes prolonged into a blade-like portion to 8 cm.
Tubercles	deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy.

	Eleocharis quadrangulata	Eleocharis baldwinii
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Shallow water of freshwater marshes, ditches, wet meadows, and lake shores. 100–200 m. WV. CA; south to Mexico; eastern North America. Exotic. Eleocharis quadrangulata is a robust spikerush with long, pale spikes and rectangular culms.
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. ovata, E. palustris, E. parishii, E. parvula, 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: 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	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 quadrangulata

Eleocharis baldwinii

four-angled spikerush, square-stemmed spikerush

Habit

Plants perennial; rhizomes 1.5–4 mm thick, longer internodes 3–8 cm, tubers absent.

Culms

acutely quadrangular; (30)45–105 cm × (1)2–5.4 mm.

Spikes

(15)20–76 × 3–5(6) mm;

proximal scale empty; amplexicaul; (1)2.2–5.4 mm; floral scales (28)45–135, 2–3 per mm of rachilla; (4)4.5–6.2 × 2.8–5 mm;

apex rounded to obtuse.

Flowers

perianth bristles 6–7, often markedly unequal; shorter than achene or some equaling tubercle;

anthers 2.3–2.9 mm;

stigmas 3, sometimes 2.

Achenes

biconvex, 1.8–3 × 1.3–2 mm; almost smooth to markedly sculptured at 10–15×; each face with 19–38 rows of almost linear, transversely elongated cells; which are sometimes isodiametric at achene base.

Distal leaf sheaths

persistent;

apex narrowly acute to acuminate, sometimes prolonged into a blade-like portion to 8 cm.

Tubercles

deltoid to high-pyramidal or lanceoloid, 0.7–1.5 × 0.4–1 mm, often spongy.