While giant hogweed is one of the UK's most well-known poisonous plants, many people don't realise it is frequently mistaken for harmless lookalikes such as cow parsley, common hogweed, and wild angelica.
'June is when giant hogweed becomes much more noticeable because the plants have put on most of their growth,' says David Denyer, flower and garden expert at Eflorist. 'The danger comes from the plant's sap – if the sap gets onto your skin and is then exposed to sunlight, it can cause severe blistering and burns that may take weeks or even months to heal.'
To help you safely identify the dangerous plant, we've shared the key warning signs to look out for and what to do if you spot it growing in your garden.
How to identify giant hogweed
The key things to look out for include:
- Size (2–5 metres tall)
- Thick hairy stems with purple blotches
- Huge jagged leaves
- Large flower heads (up to 80cm across)
One of the easiest ways to identify giant hogweed is by its size. Mature plants can grow between two and five metres tall, making them far larger than most of the ones people commonly mistake them for.
'The stems are thick, hollow, and covered in coarse white hairs, with distinctive purple blotches or streaks,' explains David. 'The leaves are also huge, often growing over a metre across, with deep, jagged cuts that give them a very dramatic appearance.'
Many of the plants people mistake for giant hogweed belong to the same family and produce similar umbrella-shaped clusters of white flowers, which is why they’re so often confused.
'When flowering, the flower heads are another giveaway – they form huge clusters of small white flowers that can reach up to 80 centimetres across, which are typically far larger than those seen on cow parsley, common hogweed, and wild angelica,' David tells us.
If you're unsure, it's always best to keep your distance and avoid the plant until you’ve identified it properly.
What to do if you find giant hogweed
Think you've found giant hogweed? The most important thing is not to touch it.
'Keep children and pets away from the area, and avoid attempting to remove large plants without appropriate protective clothing, as even a small amount of sap can cause a reaction,’ says David.
For those who find the plant growing on public land, report it to your local council or landowner. 'If it's growing in your own garden, consider seeking professional advice if you're unsure how to remove it safely,' adds David.
If you do come into contact with the sap, wash the area thoroughly with soap and water as soon as possible. After this, keep it covered from sunlight for at least 48 hours.
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