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Weed Identification

bulbous bluegrass



Scientific Name

Poa bulbosa


Bulbous bluegrass is a cool-season perennial that grows from basal bulbs and form densely tufts that grows from 6 inches to 2 ft tall.


Leaf blades are narrow (1-3mm wide) and 2 to 6 inches long, flat or loosely rolled with a white membranous ligule (3mm). The leaves are green to grayish blue in color and hairless.

Identifying Characteristics

When the bulblets are present bulbous bluegrass can easily be identified. The bulbs lay dormant until the weather begins to cool, leaves emerge from the bulbs and grows from fall to early spring. A distinguishing characteristic is that the stems are thickened and bulb-like at the base. Bulbous bluegrass is similar to onion and garlic in that it produces aerial bulblets. However, unlike onion and garlic bulbous bluegrass has flattened leaves and stems are not hollow.

Flower Seed Head

It produces 2 to 5 inch long panicles. The flowers develop into leafy bulblets that turn dark purple at the base. The dark purple bulblets contain a rudimentary plant that does not develop until after an extended dormant period. Blooming period is early spring.

Seed Fruit

Fruit is a small bulblet that has one or more small basal leaves attached. The leaves are green and narrowly shaped and grow up to 1 inch long.

Where Found

It is common in the northeastern U.S. and Oklahoma to North Dakota. It is found in disturbed sites, roadsides, abandoned fields, woodlands, and grasslands. It is best adapted for shallow soils, and tolerates a wide range of environmental conditions. It does best in full sun to light shade, moist to dry conditions and any soil type. It thrives in cool weather; however, when it turns hot it turns brown and goes dormant.

Leaf Hair on Upper Surface

no hairs

Leaf Arrangement

folded in bud

Mature Leaf Width

less than 5 mm





Life Cycle



not present



Ligule Length

more than 3 mm

Plant Type