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Weed Identification

tall oatgrass

Family

Poaceae

Scientific Name

Arrhenatherum elatius

Other Common Names:

tall meadow oat
onion couch
false oatgrass
tuber oat-grass

Habit

A perennial bunch-type grass that can grow 3 to 5 ft tall

Leaves

Leaf blades can be up to 12 inches long and 2 to 12 mm wide, are flat, hairless, and rough to the touch. The leaf has a short membranous ligule (1.5 to 2 mm), and the leaf sheaths are hairless.

Identifying Characteristics

Tall oatgrass, is a perennial, cool-season bunchgrass generally grown in Europe where it once was a component of the grasslands. Culms are erect, from 3 to 5 feet tall. It is one of the most drought tolerant cool-season grasses.

Flower Seed Head

Seed heads are narrow panicles 3 to 10 inches long and up to 2 inches wide with long, twisted, angled, exposed awns.

Seed Fruit

Seed grain are yellowish and hairy approximately 3.5 mm long with an elliptical shape

Where Found

Tall oatgrass has been introduced into the United States from Europe. It can establish in meadows, fields, open ground, waste places, and roadsides from south to Georgia, Louisiana, New Mexico, and California. Adapted to excessively drained low fertility soils.

Leaf Hair on Upper Surface

hairs from base to tip

Leaf Arrangement

rolled in bud

Mature Leaf Width

Varies: 
less than 5 mm
6 to 15 mm

Stem

flat or oval

Seedhead

panicle

Life Cycle

perennial

Auricle

not present

Ligule

membrane

Ligule Length

1-2 mm

Plant Type

Grass