Giant hogweed, Giant cow parsnip
FULL SCIENTIFIC NAME
Heracleum mantegazzianum Sommier & Levier
FAMILY NAME COMMON
FAMILY SCIENTIFIC NAME
Heracleum mantegazzianum is a herbaceous biennial or monocarpic perennial that can grow up to 4.3-5.8 m (15-20 ft.) in height. The stem is hollow and usually blotched with purple. Both the leaf stalks and stem produce pustulate bristles. The stem can be 4.8-9.6 cm (2-4 in.) in diameter. The leaves are ternate or ternate-pinnate with pinnately lobed lateral segments. They can be up to 3 m (9.8 ft.) in breadth. Heracleum mantegazzianum flowers from June-July. The inflorescence has many white florets (with petals about 1 cm) that form a flat-topped umbel. Each inflorescence can have a diameter of up to 0.72 m (2.5 ft.). The fruits are dry and elliptic, measuring 8-11 mm (0.3-0.4 in.) long and 6-8 mm (0.25-0.3 in.) wide. The fruits have brown resin canals that can be up to 1 mm (0.04 in.) in diameter. Page References Bailey 751, Flora Europaea 2:366, Gleason & Cronquist 382, Holmgren 358, Magee & Ahles 785. See reference section below for full citations.
Heracleum maximum Bartr. (synonym: H. lanatum Michx.) (common cow parsnip), Pastinaca sativa L. (wild parsnip), Angelica atropurpurea L. (purple stem angelica), Phytolacca americana L. (pokeweed), Lactuca biennis (Moench) Fern. (blue lettuce) Click here for a link to the Giant Hogweed comparison table
Other species not shown in table: Cicuta maculata L. (spotted water hemlock) Picture of C. maculata, Conium maculatum L. (poison hemlock)
Heracleum maximum is often found along stream banks, and the seeds can be transported downstream by water.
Heracleum mantegazzianum is a native of the Caucasus Mountains and southwest Asia. It was introduced as a garden plant in the United States, Europe, Canada and the United Kingdom. It was reported in Canada in southern Ontario around 1950. In the United States it is has been reported from Washington, Oregon, Illinois, Michigan, New York and Pennsylvania. In New England it has been identified in Maine, Vermont, Massachusetts and Connecticut.
HISTORY OF INTRODUCTION IN NEW ENGLAND
Heracleum mantegazzianum was introduced as early as 1917 as a garden curiosity, and most likely reached New England through cultivation in gardens.
HABITATS IN NEW ENGLAND
Edge, Floodplain Forest, River or Stream, Roadside, Vacant Lot, Yard or Garden. Heracleum mantegazzianum is present along roadsides, in vacant lots and along streams and rivers. It prefers rich, moist soil, in semi-shade conditions.
Heracleum mantegazzianum can outcompete species for habitat, especially in riparian zones, and it may cause increased soil erosion. This plant is on the federal noxious weed list because of its poisonous sap. This sap makes skin very sensitive to UV radiation, causing blistering and sever burns. Caution should be taken when handling this weed. Removing it manually becomes very difficult because of the danger caused by its sap.
Documentation required: Specific photograph or mounted snippet showing the inflorescence with scale so as to ascertain the size. Best time for documentation: Summer
Integrated Taxonomic Information System Taxonomic information about the species
The PLANTS Database General information and map
USDA, ARS, National Genetic Resources Program General and taxonomic information
Federal Noxious Weed Inspection Guide General information including natural history
Bailey, L. H. 1949. Manual of Cultivated Plants. Macmillan, New York.
Caffrey, J.M. 1999. Phenology and long-term control of Heracleum mantegazzianum. Hydrobiologia 415, 223-228.
Dodd, F.S., L.C. de Waal, P.M. Wade and G.E.D. Tiley. 1994. Control and management of Heracleum mantegazzianum (giant hogweed). In: de Waal, L.C. et al. (eds) Ecology and management of invasive riverside plants. John Wiley & Sons, Chichester, pp. 111-126.
Gleason, H.A. and A.C. Cronquist. 1991. Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed. New York Botanical Garden, Bronx, New York.
Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. New York Botanical Garden, Bronx, New York.
Magee, D.W and H.E. Ahles. 1999. Flora of the Northeast. University of Massachusetts Press, Amherst.
Morton, J.K. 1978. Distribution of giant cow parsnip (Heracleum mantegazzianum> ) in Canada. Canadian Field Naturalist. 92(2):182-185.
Pysek, P. and A. Pysek. 1995. Invasion by Heracleum mantegazzianum in different habitats in the Czech Republic. Journal of Vegetation Science. 6:711-718.
Tutin, T.G., V.H. Heywood, N.A. Burges, D.M. Moore, D.H. Valentine, S.M. Walters, D.A. Webb, Eds. 1968. Flora Europaea, Volume 2. Cambridge University Press, London, UK.
USDA, NRCS. 2001. The PLANTS Database, Version 3.1. (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.