Annual Bluegrass (surrounding the central weed)
Poa annua · Cool-season Annual (sometimes short-lived perennial), C3
Grass Family
Poaceae, Subfamily Pooideae, Tribe Poeae
Grass Category
Invasive/Weed Grass (often found in Lawn/Turf and Golf Course Grass)
Variety / Cultivar
Common Poa annua (wild type)
Hardiness Zones
USDA Zones 3-10; survives winter by staying green; dies off or goes dormant during extreme summer heat.
About This Grass
A low-growing, clump-forming grass that is easily identified by its prolific white seed heads and yellowish-green color. It stands out in darker turf and quickly colonizes bare soil.
Blade Characteristics
Blade width: fine to medium (2-3mm); shape: folded; tip: boat-shaped; color: light yellowish-green; vernation: folded; ligule: membranous and long; auricles: absent.
Root System
Shallow fibrous root system; very poor drought tolerance; lacks significant thatch; rapid establishment from seed.
Growing Information
Origin Region
Native to Europe and Eurasia; widely naturalized globally in temperate climates
Growth Habit
Bunch-type to slightly stoloniferous; forms low-growing, light-green tufts
Sunlight & Water Needs
Partial sun to shade preferred but tolerates full sun; high water needs; prefers moist, compact soils with neutral to slightly acidic pH.
Mowing & Maintenance
Extremely low mowing tolerance (can survive and set seed at 0.1 inches); maintenance level: High (as a weed, it requires frequent herbicide or manual removal).
Special Characteristics
Exceptional seed production (can seed multiple times a year); high shade tolerance; very low wear tolerance; easily outcompeted in healthy, thick turf.
Ecological Information
Introduced/Invasive status in many regions; minimal wildlife value; rapid colonizer of disturbed soils; often found alongside Broadleaf Groundsel (Senecio vulgaris, pictured in center).