High Quality Content by WIKIPEDIA articles! Poa compressa (Canada bluegrass or flattened meadowgrass) is a perennial flattened meadow grass, similar to Common Meadow-grass, Poa pratensis. It is native to Europe but it can be found nearly worldwide as an introduced species. It grows in old wall tops, pavement cracks, dry stony grassland, and many types of wild habitat. It has a flattened stem, 23 30 cm tall, a close one sided panicle of grey green, with purple florets. The ligule is rounded. A perennial plant or perennial (Latin per, "through", annus, "year") is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. When used by gardeners or horticulturalists, perennial applies specifically to winter hardy herbaceous plants. Scientifically, woody plants like shrubs and trees are also perennial in their habit. Perennials, especially small flowering plants, grow and bloom over the spring and summer and then die back every autumn and winter, then return in the spring from their root-stock rather than seeding themselves as an annual plant does.