Barnyardgrass (Echinochloa crus-galli) — identification, habitat & look-alikes

Barnyardgrass is a grass found across the continental United States and one of the world's worst agricultural weeds. It is native to Asia and has been in North America since at least the 1840s.

Appearance

Growth form: A clumping annual grass up to 5 ft (1.5 m) tall. Stems are flattened near the base, which is often tinged purple or maroon. Young stems may sprawl before turning upward.
Leaves: Flat, mostly hairless blades. The easiest clue is the collar: there is no and no hairs where the blade meets the stem, which is unusual among common summer grasses.
Flowers: Dense, knobby seed heads 2.5–10 in long, upright or drooping and sometimes purplish. Blooms June through October in California.

Look-alikes

junglericeEchinochloa colona

Junglerice usually has distinctive purple bands across its leaves; barnyardgrass does not.

Why they get mixed upA close relative with similar seed heads and the same weedy habits.

late watergrassEchinochloa oryzicola

Late watergrass is generally found only in rice fields, while barnyardgrass also grows in ditches, roadsides, and other crops. The plants can be hard to tell apart from photos.

Why they get mixed upBoth are rice-field Echinochloa grasses with very similar plants.

rough barnyardgrassEchinochloa muricata

This native grass is very hard to separate without about 25x magnification. Barnyardgrass end in a thin, papery tip set off by a line of tiny hairs, while rough barnyardgrass florets stay hard right to the sharp tip.

Why they get mixed upA common native Echinochloa of moist ground across the US with nearly identical seed heads.

Where it lives

Typical habitats: crop fields
rice fields
ditches
roadsides
pond edges
Range: Found throughout the lower 48 states and southern Canada from British Columbia to Newfoundland.
Preferred conditions: Prefers moist, disturbed ground: irrigated crops, pastures, orchards, ditches, and the margins of ponds and rice fields.
Flowering: Flowers Jun–Oct
Flowers Jun–Oct

Life cycle

Seed dispersal: A single plant can make up to 40,000 seeds a year. Seeds spread in water, on birds, animals, and machinery, and most often as a contaminant in crop seed.

Name and classification

About the name: Japanese millet (Echinochloa esculenta), a small-scale grain crop in Japan, Korea, and China, is a domesticated form of this species and was once treated as its variety var. utilis.