Ragwort is deadly to some livestock

Ragwort causes irreversible liver damage to cows and horses but is very difficult to remove once established from an area.

Each plant can produce up to 150,000 seeds which can stay dormant in the soil for up to 20 years.

The Highways Agency is spending the next few weeks pulling the flowers up to stop the seeds spreading.

Ragwort hotspots on motorway verges have been identified and are being targeted for destruction.

'Serious threat'

Highways Agency assistant maintenance manager Liz Girvan said: "This time of year is critical when it comes to getting rid of ragwort.

"We have to pull them out of the ground by hand once they flower to stop the seeds spreading.

"The Agency takes the threat these plants cause to animals very seriously and we do our utmost to destroy it.