Poa annua aka Winter Grass

Poa annua is annual bluegrass, also called annual meadow grass. It belongs to the grass family, Poaceae. Its native range covers temperate Europe, Asia, and Africa. It is native to Britain and Ireland as well. This grass now grows across much of the world. Its range reaches from Arctic regions to the Antarctic. It grows in crops, lawns, and some less disturbed sites.

This low grass forms tufts with shallow, fibrous roots. Plants reach about 0.3–1.6 feet (0.1–0.5 metres) in height and width. They can reach full size within one year. The pale green leaves spread out from the plant's centre. Each narrow blade is flat, smooth, and free of hairs. The tips close into a shape like a boat's bow. Two lengthwise lines and crosswise wrinkles help identify the leaves. The blades fold inside smooth, slightly flattened sheaths. The stems have no scent.

Loose panicles hold pale flowers on fine, spreading branches. The flower clusters have a roughly pyramidal outline. Their stalked spikelets lack awns, the bristles found on some grasses. Spring is a flowering season, but plants can seed year-round. The fruit is an achene, a small, dry, single-seeded fruit. Each plant can make hundreds of seeds in one season. Seeds can stay viable underground for at least four years. Plants often die after seeding, though some live beyond one year. In North Carolina, growth starts between autumn and spring. Warm weather then brings the annual cycle to an end.

It grows in full sun or partial shade. Moist soil suits it, including clay, loam, sand, and chalk. Sources differ on pH, but very acid soil is less suitable. It tolerates mowing, foot traffic, and frozen ground. The RHS rates its cold hardiness as H7. North Carolina State lists USDA zones 4–8. The RHS suggests it for wildlife gardens and wildflower meadows. Yet it can crowd out other plants and crops.

Its fast growth and lasting seed supply make control difficult. North Carolina State does not recommend it as lawn grass. The RHS reports few usual pest or disease problems. North Carolina State also links it with gray snow mold. Its pollen can cause hay fever. The supplied sources give no clear evidence of edible parts. They also do not establish its safety for people or pets.