OregonFlora: Paspalum distichum

	Paspalum distichum
	knotgrass
Habit	Plants perennial, 5–65 cm tall, strongly rhizomatous.
Culms	erect or ascending; lateseason shoots bulbous at the base.
Leaves	sheaths mostly glabrous, sparsely long-pubescent distally; those growing under water densely hairy; blades flat or folded; to 14 cm × 1.8–11.5 mm, glabrous or sparsely long-pubescent.
Inflorescences	V-shaped panicles, 1.4–7 cm; branches usually 2(3), 1.5–5.5 cm; spikelets in rows on one side of branch.
Spikelets	solitary or rarely paired, 2.4–3.2 × 1.1–1.6 mm, 2 florets.
Glumes	1 or 2; lower glumes absent or triangular and to 1 mm; upper glumes 2.4–3.2 mm, 3-veined, sparsely short-pubescent on the back.
Caryopses	1.9– 2.1 mm, yellow.
Lemmas	lower lemmas as long as upper glumes but glabrous; upper lemmas 2.5–3 mm, obscurely 3-veined; hard; straw-colored; shiny, glabrous; tips acute; awnless.
Anthers	1–1.5 mm.
2n	=20, 30, 40, 48, 60.

	Paspalum distichum
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Wet ditches, marshes, river banks. 0–1200m. Col, Est, Owy, Sisk, WV. CA, ID, NV, WA; northwestern and southern US; tropical and warm-temperate areas worldwide. Native. Paspalum distichum is a strongly rhizomatous grass usually with two short panicle branches. Cynodon dactylon also has spike-like inflorescence branches and is equally rhizomatous, but it usually has more inflorescence branches and laterally flattened spikelets with two glumes. Digitaria species are loosely cespitose and often have smaller spikelets.
Source	Flora of Oregon, volume 1, page 443 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	P. dilatatum
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

Paspalum distichum

knotgrass

Habit

Plants perennial, 5–65 cm tall, strongly rhizomatous.

Culms

erect or ascending; lateseason shoots bulbous at the base.

Leaves

sheaths mostly glabrous, sparsely long-pubescent distally; those growing under water densely hairy;

blades flat or folded; to 14 cm × 1.8–11.5 mm, glabrous or sparsely long-pubescent.

Inflorescences

V-shaped panicles, 1.4–7 cm;

branches usually 2(3), 1.5–5.5 cm;

spikelets in rows on one side of branch.

Spikelets

solitary or rarely paired, 2.4–3.2 × 1.1–1.6 mm, 2 florets.

Glumes

1 or 2;

lower glumes absent or triangular and to 1 mm;

upper glumes 2.4–3.2 mm, 3-veined, sparsely short-pubescent on the back.

Caryopses

1.9– 2.1 mm, yellow.

Lemmas

lower lemmas as long as upper glumes but glabrous; upper lemmas 2.5–3 mm, obscurely 3-veined; hard; straw-colored; shiny, glabrous;

tips acute; awnless.

Anthers

1–1.5 mm.

=20, 30, 40, 48, 60.

Paspalum distichum

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Wet ditches, marshes, river banks. 0–1200m. Col, Est, Owy, Sisk, WV. CA, ID, NV, WA; northwestern and southern US; tropical and warm-temperate areas worldwide. Native.

Paspalum distichum is a strongly rhizomatous grass usually with two short panicle branches. Cynodon dactylon also has spike-like inflorescence branches and is equally rhizomatous, but it usually has more inflorescence branches and laterally flattened spikelets with two glumes. Digitaria species are loosely cespitose and often have smaller spikelets.

Source

Flora of Oregon, volume 1, page 443
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa

P. dilatatum

Web links