Giant Hogweed

Heracleum mantegazzianum

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  3. Giant Hogweed


Giant Hogweed was introduced into the UK by the Victorians as an ornamental plant for lakesides and gardens. But it wasn't until the 1970s that its presence as an alien species really gained notoriety. At this time, many children started to display blisters as a result of touching the plant's sap while using the stems to make pea-shooters or telescopes; the summer sunlight made the skin sensitive to the irritants in the plant, causing the skin to redden. Today, it is widely acknowledged that neither gardeners nor conservationists should attempt to cut the plant down (exposing its sap) as its toxins can cause serious, recurring skin damage.

How to identify

Giant Hogweed is an immensely tall umbellifer (member of the carrot family) which displays large, white, umbrella-like clusters of flowers from June to July. Its hollow stem is ridged and purple-spotted, and its leaves are large and divided.

Where to find it

Scattered throughout mainland UK and quite common in Northern Ireland.


When to find it

  • June
  • July
  • August

How can people help

Giant Hogweed is an introduced species that has become widespread and naturalised in the UK, crowding out our native wildflowers and causing problems for our native wildlife. The Wildlife Trusts work with researchers, scientists and other conservationists to monitor changes in our native wildlife to determine the effects of environmental change, such as the introduction of new species or climate change. You can help: volunteer for your local Trust and you'll be able to monitor populations and survey habitats, adding to a growing bank of data.

Species information

Common name
Giant Hogweed
Latin name
Heracleum mantegazzianum
Height: up to 4m
Conservation status
Introduced, invasive species.