where does giant hogweed grow in the us
Heracleum mantegazzianum Giant hogweed was among many foreign plants introduced to Britain in the 19th century as ornamental plants. It is now widespread throughout the British Isles, especially along riverbanks. By forming dense stands, they can displace native plants and reduce wildlife habitats.[9] It has spread in the northeastern and northwestern United States, and southern Canada and is an invasive species in Germany, France, and Belgium, overtaking the local native species, Heracleum sphondylium.[9] Giant hogweed was introduced to the Baltics during the Soviet era as fodder for cattle.[10]
Invasive species Weeds reduce yield in agriculture, though they may provide essential nutrients. Some deep-rooted weeds can "mine" nutrients (see dynamic accumulator) from the subsoil and deposit them on the topsoil, while others provide habitat for beneficial insects or provide foods for pest species. Many weed species are accidental introductions that accompany seeds and imported plant material. Many introduced weeds in pastures compete with native forage plants, threaten young cattle (e.g., leafy spurge, Euphorbia esula) or are unpalatable because of thorns and spines (e.g., yellow starthistle). Forage loss from invasive weeds on pastures amounts to nearly US$1Â billion in the U.S. alone.[66] A decline in pollinator services and loss of fruit production has been caused by honey bees infected by the invasive varroa mite. Introduced rats (Rattus rattus and R. norvegicus) have become serious pests on farms, destroying stored grains.[66]