Heracleum sphondylium, common names Common Hogweed or Cow parsnip, is a herbaceous perennial or biennial plant of the family Apiaceae. It is an umbelliferous plant, in the same group as fennel, cow parsley, ground elder and giant hogweed. Umbelliferous plants are so named because of the umbrella-like arrangement of flowers they produce.
This plant has pinkish or white flowers with 5 petals. They are arranged in large umbels of up to 20 cm of diameter with 15 to 30 rays. The peripheral flowers have a radial symmetry. Flowering typically occurs between June and October. The flowers are pollinated by insects (usually bees, wasps and flies) (entomogamy) The small fruits are flattened and winged, elliptical to rounded and glabrous, up to 1 cm long. The seed dispersal is by wind (anemochory).
Description adapted from Wikipedia: http://en.wikipedia.org/wiki/Common_Hogweed