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Heracleum mantegazzianum

LHPrism Status 
Tier 2 - Emerging
LHPRISM Notes 

Heracleum mantegazzianum: Giant Hogweed

Plant Identification:

  • Growth form: perennial, monocarpic herb growing as high as 5 meters
  • Inflorescences: white, sometimes pinkish, compound umbels up to 80 cm across with 30-150 rays
  • Flowers: pedicles 10-20 cm long with petals up to 12 mm long
  • Stem: rigid, stout, and 5-10 cm in diameter. stems and leaf stalks are completely or spotted reddish-purple in color, hollow, and produce postulate bristles that produce phototoxic sap
  • Leaves: alternate with lower leaves 1-2.5 m long, compound, irregularly shaped, deeply lobed, and irregularly toothed
  • Fruit: dry shizocarps consisting of two mericarp, elliptical, flattened seeds

*This species exudes a sap that sensitises the skin to ultraviolet radiation which can result in severe burns

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