rough bluegrass

Family

Poaceae

Scientific Name

Poa trivialis

Synonyms (former Scientific Names):

Poa attica

Habit

Spreads both by seed and stolons unlike annual bluegrass, which spreads only by seeds. Most growth occurs in fall and spring. Most leaves die back during the summer, but plants quickly recover and sprout the following fall.

Leaves

Leaves are light green (also can have a reddish hue to leaves and stems), lack hairs, lack auricles, are narrow with pronounced mid-vein, and have a membranous ligule that is pointed. The ligule can range from less than 1 mm to 6 mm depending on plant size and stress. Leaves are creased because they are folded in the bud and leaf tips are boat-shaped, which is a characteristic of the genus Poa. It is also common for leaves to have wavy margins toward the leaf base. The base of mature plant tillers is wavy or bumpy and feels rough to the touch. Leaves arise predominately from stems that lay flat or from stolons; unlike annual bluegrass, which is a bunch-type grass and has leaves that originate basally.

Identifying Characteristics

Folded in the bud, have pointed membranous ligule, lack auricles, have stolons, and can have a reddish hue to leaves and stems. Plants resemble annual bluegrass but grow in a round patchy nature and have stolons.

Flower Seed Head

Seedhead is a pyramid-shaped panicle that is large (15 to 20 cm long and 3 to 6 cm wide) or three to six times longer than annual bluegrass seedheads. Each spikelet has two to three flowers and is 3 to 4 mm long. When mature plants bloom, seedheads may be 50 to 100 cm (20 to 40 inches) tall.

Seed Fruit

Seed are shiny and yellow when rubbed clean. Seed are elliptic and 2.2 mm long with shaft and 1.2 mm long rubbed clean.

Where Found

Roughstalk bluegrass is an ever increasing weed problem in fine turfgrass. Plants are native to low lying wooded areas and waste places but are used in areas of the southern US as an overseeded species. Seed contaminates are increasing as more roughstalk bluegrass is grown to meet southern overseeding needs. In the north, plants survive the mild summer and become weed problems in desirable Kentucky bluegrass, tall fescue, perennial ryegrass, and creeping bentgrass turf.