Species

Heracleum mantegazzianum

Etymology

Heracleum: Named after the classical Greek hero Herakles (Hercules) who is said to have discovered the plant's healing properties.

Common Name(s)

giant hogweed

Authority

Heracleum mantegazzianum Sommier & Levier

Family

Apiaceae

Brief Description

WARNING: the NZ Ministry of Primary Industries (MPI) says"Giant hogweed is poisonous to humans. Touching it, or exposure to dust from weed-eating, can irritate skin and cause blisters and swelling. The toxin actually causes photosensitisation so that the skin reacts badly to sunlight."http://www.biosecurity.govt.nz/pests/giant-hogweed "Giant hogweed is a perennial that grows 4-6 m in height. It has stout dark-reddish-purple stems, and spotted leaf stalks with sturdy pustulate bristles which contain a toxic sap. The stems and stalks are hollow, the stems being 5-10 cm in diameter. Giant hogweed has extremely large leaves (up to 1.5 m) and tuberous root stalks. When the plant is two to three years old it produces large umbrella-like clusters of greenish-white flowers. It usually grows on the banks of rivers or creeks." (ibid)

Flora Category

Vascular - Exotic

Structural Class

Dicotyledonous Herbs other than Composites

Features

A biennial or perennial herb, up to 5 m tall; with a taproot or fascicled fibrous root; stems hollow; leaves compound with 3 leaflets, lower ones to 2.5m long; inflorescence, loose compound umbels; flowers small, perfect; fruit a schizocarp (splitting between the carpels) into two 1-seeded sections (mericarps); the mericarps are elliptical, 7-12 mm long, 6-10 mm broad, with brown oil tubes (vittae) conspicuously expanded at their lower ends (up to 1 mm wide).

Similar Taxa

H. spondylium (cow parsnip). Hogweed has purple blotches on the stems and petioles.

Flower Colours

White

Fruiting

Mericarps 10 mm long with conspicuous oil canals (vittae) - see Flora of NZ 4: 123, Fig 12

Year Naturalised

1968

Origin

SW Asia

Reason for Introduction

Possibly ornamental.

Control Techniques

MPI advise "Contact your regional council to determine the status of this species and responsibility for control and/or advice on control."

This page last updated on 2 Jan 2017