Bulbous bluegrass

Poa bulbosa

Keys to Identification

Stems are bulblike at the base
Flowers are purplish leafy bulblets
Only grass known to produce bulblets

Family

Poaceae – Grass family

USDA Code

POBU

Legal Status

Colorado Noxious Weed List C

Identification

Lifecycle

Short-lived perennial

Growth form

Tuft or sod forming grass. Plants are 6-24 inches tall

Flower

Flowers are arranged in 2-5 inch long panicles. Flowers develop as leafy bulblets with a dark purple base, 4-6 bulblets on each spikelet. May-June

Seeds/Fruit

Bulbous bluegrass produces asexually in the US, though in Europe it produces seeds

Leaves

Leaves are narrow and 2-6 inches long, flat or loosely rolled and keeled at the base

Stems

Stems are flattened near the base, upper stems are round

Roots

Fibrous roots regrow each season and have a relatively short lifespan

Seedling

Early season

Similar Species

Exotics

Kentucky bluegrass

Natives

N/A

Impacts

Agricultural

Bulbous bluegrass outcompetes desirable vegetation and offers little biomass as forage. Invades degraded rangelands and pastures

Ecological

Mature plants are palatable to rodents and birds due to high starch and fat content

Habitat and Distribution

General requirements

Found in disturbed sites, roadsides, hay fields, and rangeland. Typically found in areas that receive 12-40 inches annual precipitation

Distribution

Reported in western and Front Range counties in Colorado. Found throughout the western and mid-Atlantic regions of the US

Historical

From Europe, Asia, and North Africa. Introduced accidentally to the US in the early 1900’s when it was being evaluated for turf, erosion control, and pasture

Biology/Ecology

Life cycle