Staff working on the M20 are being warned to stay away from a deadly plant growing at the side of the road.

A cordon is in place to block workers from touching poisonous hemlock, which can kill if eaten.

The cordon has been put in place just days after construction work began on the £92million smart motorway scheme.

A Highways England spokesperson said: "We have found some hemlock while clearing vegetation for our work on the M20 between junctions three and five during the last month, and we are currently clearing this.

"There is no public access to this land, and the hard shoulder has now been cordoned off due to construction starting on the motorway improvements. Our signs are to remind our clearance team of it to ensure they take all necessary precaution and wear full protective clothing."

Growing up to eight feet in some cases, hemlock resembles other plants from the parsley family. It has hairless hollow stalks with purple blotches.

Hemlock facts

1 It can kill you

Hemlock is a notoriously poisonous plant, and can kill you in under three hours.

It works by disrupting the central nervous system, causing respiratory collapse.

The root contains the greatest concentration of toxin, but all parts of the plant are highly toxic and should not be ingested.

Even touching the plant could generate a reaction in some people, and can be fatal even in tiny amounts.

2 It's historical

In ancient Greece, hemlock was used to poison condemned prisoners.

Historically, the plant is well-known for being the drug given to famous Greek philosopher, Socrates, at his execution.

He was accused of corrupting the youth of Athens and refusing to recognise the gods of the state.

Most sources state that he ingested the plant either mixed with water or as a tea.

3 It has a distinctive smell

The plant, which is often confused with cow parsley, can be distinguished by the unpleasant mousey smell of its foliage.

It also has purple-spotted stems, finely divided leaves and small white flowers in the summer.

Hemlock leaves are also slightly darker than cow parsley leaves, and they are finer and more feathery in appearance.

Be extremely careful if you ever decide to make cow parsley soup - a mistake could be fatal.

4 It has lots of different names

Hemlock can also be referred to as woomlick, beaver poison, bunk, poison parsley, devil's flower and lady's lace.

It is also sometimes referred to as break-your-mother's-heart and scabby hands - which tells you all you need to know really.

5 It can be used to treat illness

Despite serious safety concerns, the plant is sometimes used to make medicine.

It can help to treat breathing problems such as bronchitis, whooping cough and asthma.

It has also been used on patients with epilepsy, anxiety, mania, Parkinson's disease and skin infections.

This goes without saying, but do not try this at home.