Perennial Sow Thistle (Sonchus arvensis L.) in iowa

Perennial sow thistle (Sonchus arvensis L.) has wide geographical distribution. It occurs throughout Europe to 70° 35\u27 North, in Siberia, Caucausus and lower Asia to Afghanistan. It is naturalized in India, Ceylon, Japan, North Africa, Australia and New America. Perennial sow thistle thrives in cultivated and uncultivated ground and in a wide range of soils. Its seeds have a high percentage of germination, without requiring a rest period. The plant may be propagated from cuttings of the root less than half an inch long as well as from the short upright rootstocks. The flowers are perfect; in seven days after they open under ordinary field conditions during midsummer, the seed is mature. This cosmopolitan with its variety levipes Koch has been known to occur in 25 counties in Iowa. Locations in which it has gained a foothold are lumber yards, elevators, stockyards and railway stations, where it occurs in small patches. While perennial sow thistle is not yet commonly established in Iowa fields, its habits of growth and propagation fit it for adaptation and rapid spread in a wide range of environment