Giant hogweed Heracleum mantegazzianum is a Federally listed noxious weed. Its sap, in combination with moisture and sunlight, can cause severe skin and eye irritation, painful blistering, permanent scarring and blindness. Contact between the skin and the sap of this plant occurs either through brushing against the bristles on the stem or breaking the stem or leaves. Giant hogweed is a biennial or perennial herb in the carrot family Apiaceae which can grow to 14 feet or more. Its hollow, ridged stems grow 2-4 inches in diameter and have dark reddish-purple blotches. Its large compound leaves can grow up to 5 feet wide. Its white flower heads can grow up to 2 1/2 feet in diameter. Giant hogweed grows along streams and rivers and in fields, forests, yards and roadsides. It prefers open sites with abundant light and moist soil but it can grow in partially shaded habitats, too. Giant hogweed can thrive in many habitats. It grows particularly well in areas where the soil has been disturbed, such as on wastelands, riverbanks, roadsides and along railroads. Its size and rapid growth allow it to quickly dominate an area, if the conditions are right. The earliest recording of the plant in the U.S. is 1917, from Highland Park, New York outside of Rochester
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