Common milkweed is a flowering plant that reaches up to 6 feet (1.8 meters) high. Native to North America, it has been naturalized throughout many other parts of the world. This species is considered invasive in some areas. To many people, however, it is an important plant, not only as an attractive garden addition, but also as a habitat and food source for many insect and beetle species.
This species is considered invasive because of its rapid growth rate and because it spreads quickly. Common milkweed is able to reproduce both sexually and asexually. Sexual reproduction involves insect pollination, followed by seed production and dispersal. Flowers are formed in dense clusters in shades of white to purple, which die back after insect pollination. After the flowers die, seed pods appear, which eventually dry out and split, releasing the seeds for dispersal.
Asexual reproduction of common milkweed is rhizomatous spread. Common milkweed produces long trailers beneath the soil, which are referred to as rhizomes. The rhizomes travel away from the parent plant and produce small shoots, which break through the soil to form a new plant which is an independent duplicate of the parent. Common milkweed grows in dense, outward spreading clumps due to rhizomatous reproduction.
Forming large, dense clumps means that the plant quickly dominates and excludes slower spreading and smaller native species, putting some more delicate native species at risk of localized extinction in some regions. Another reason for the invasive nature of this species is that it is tolerant of most soil types except heavy clay, and can grow in soils which are not nutrient rich. It can be found in a wide range of habitats, from pasture and meadow land, to roadsides and the edges of woodland, providing there is some nutrient content and good drainage.
Although common milkweed is toxic to humans if eaten raw, when properly cooked most parts of the plant are edible and have been eaten by indigenous peoples for centuries. This plant also has a long history of being used for medicinal purposes, such as a contraceptive, a pain reliever, a laxative, and a cure-all for respiratory, digestive, and sexually transmitted issues. It is still used as a herbal treatment for warts.
Common milkweed is highly toxic to poultry; it can be poisonous to some other animals if large quantities are eaten, and so this plant is seldom eaten by grazing animals unless other food sources are particularly scarce. Many different insects, such as bees, wasps, and butterflies, are attracted to common milkweed. Many of these species use the plant as both shelter and as a primary food source.