a tall plant, Heracleum mantegazzianum, of the parsley family, native to Russia and now naturalized in the U.S., having very large leaves and broad, white flower heads somewhat resembling Queen Anne's lace: can cause an allergic rash when touched by susceptible persons.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
British Dictionary definitions for giant hogweed
an umbelliferous garden escape, Heracleum mantegazzianum, a tall species of cow parsley that grows up to 3 1/2 metres (10 ft) and whose irritant hairs and sap can cause a severe reaction if handled: Also called: cartwheel flower
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012