Be toxic species savvy
There are hidden dangers everywhere whilst out in the countryside or walking along river or canal paths that the public should be aware of. Innocent looking plants that are either nestled in among the ferns and woodland flowers, or large imposing plants that tower up to 3 metres high. But would you know which ones can cause harm to health or even kill you?
This article provides the information you need to know about the UK’s most noxious (toxic) plants and how to spot them so you and your pets can keep safe. Information that is also vital for those working in the environments that these plants thrive in. We’re starting with species that are most toxic to humans and pets, and following up with some species that are toxic to animals.
Hemlock water dropwort
This innocent looking plant is extremely toxic to humans and wildlife, death can apparently occur in a few hours after eating it. Whilst this may sound a tad dramatic, multiple deaths have been recorded in the UK from people mistaking it for an edible herb. Found along waterways and river banks, often growing among other water loving plants.
The dangers
Also known as “Dead Man’s Fingers” because when the river bank erodes the roots appear from the ground like the blackened hand of a dead man – this invasive species is deemed the most poisonous plant in the UK, with death occurring only a few hours after eating it. All parts of the plant contain toxic alkaloids that can be fatal, even in small amounts. The toxinss can affect nerve impulse to the muscles and eventually kill through respiratory failure.
- Do not touch any part of this plant
- If contact is made with this plant do not put unwashed hands on your face, eyes or in your mouth
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
The plant grows in clumps with ‘grass’ green branch like leaves and small clusters of creamy white flowers that resemble cow parsley. The flower heads grow from a central stalk in a roundel pattern, typically with 15 flower clusters per head.
Hemlock
Don’t be fooled by this plant’s delicate appearance, all parts of the Hemlock plant are poisonous, naming this as the most toxic plant to both humans and animals growing in Britain. All parts of the plant are poisonous, even the dead canes can remain toxic for up to 3 years and ingesting only a small amount of plant material can be fatal. It contains a powerful neurotoxin called Oenanthe toxin, which triggers spasmodic convulsions, usually followed by sudden death.
The dangers
Hemlock is highly toxic to livestock and humans and can be fatal. Symptoms display after 30 minutes to three hours depending on the amount ingested. Poisoning affects the nervous and respiratory systems and can lead to respiratory failure. Symptoms include trembling, burning sensation in digestive tract, increased salivation, dilated pupils, muscle pain, weakness, rapid followed by decreased heart rate, loss of speech, convulsions and unconsciousness. Even when touched, the plant can generate a painful rash, or painful burning of the eyes.
- Do not touch any part of this plant
- If contact is made with this plant do not put unwashed hands on your face, eyes or in your mouth
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
Similar to Hemlock water dropwort in appearance, but with different shaped and darker green leaves, Hemlock grows on river banks, forming large clusters of tall stems with small white flowers that grow in a similar patter to Hemlock water dropwort, but with typically fewer flower clusters per head. The leaves look very similar to the herb Chervil, so foragers need to be extremely confident they know the difference.
Ragwort
Classed as an ‘injurious’ weed, due to its toxicity levels, this species can grow up to 1 metre high, stems are tough and often tinged red/purple near the base, with characteristic dark green leaves and yellow daisy-like flowers. As a perennial the above ground growth completely dies off in winter but its seeds remain dormant in the soil for up to 20 years – making Ragwort a real issue for farmers and landowners.
The dangers
Ragwort is one of the most frequent causes of plant poisoning of livestock in Britain, with equines and bovines being more susceptible than others – particularly the young. It can also be poisonous to humans and has been suspected of causing liver damage in those who have tried to manually remove it without wearing protective clothing. Ragwort acts as a cumulative poison, eventually destroying the liver, and a small intake of ragwort over a long period can be just as damaging as a large intake on a single occasion. Word of warning – be very careful when around this plant!
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
Ragwort grows prolifically in meadows and pasture land, and is most noticeable when the bright yellow ‘daisy-like’ flower heads appear. When the flowers die back they turn dark brown. It has tall stems that have an abundance of curly edged leaves from top to bottom.
Giant hogweed
Giant hogweed is a danger to man, wildlife and biodiversity, causing hogweed burns, hogweed rash and hogweed blisters. It is often associated with riparian habitats, where waterways can provide corridors along which it can spread. As well as river margins, it can also be found on roads and railways, derelict land and rubbish tips. Not to be mistaken for its smaller variety – Common hogweed, this species gets its name for its scale – Giant hogweed is an impressive sight!
The dangers
Giant hogweed is highly invasive, but more concerning is its ability to inflict serious injury and even blindness on people or animals that come into contact with the plant. All parts of the Giant hogweed plant, including the hairs on the stems and leaves (which can penetrate light fabric) contain a toxic sap that can cause severe skin blistering. Humans, pets and wildlife can all be affected by contact with Giant hogweed. The blistering and dense post-inflammatory hyper-pigmentation is visible after 3-5 days, last for several months and recur for up to 6 years, causing flare ups whenever the skin is exposed to sunlight. Contact with eyes can lead to temporary, or in some cases permanent, blindness.
- Do not touch or brush past any part of this plant
- If contact is made with this plant do not put unwashed hands on your face, eyes or in your mouth
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
Giant hogweed is difficult to miss – with large flower heads sitting on top of thick hairy stalks up to 3 metres high with a pale, swollen rootstock. The large leaves can reach 1 metre across. Flower umbrells can be 80 cm across and grow from a central stem, the heads first appear as a closed pod which unfurls to reveal clusters of small cream-white flowers that look like very large cow parsley.
Yellow azalea
This bright yellow flowering shrub looks like a smaller version of Rhododendron, but can be harmful if ingested. As the nectar of Rhododendron is often referred to as ‘honey’ (or ‘mad honey’) there is a danger that people could mistake Yellow azalea for Rhododendron and sample it’s nectar. Like Rhododendron it is commonly found in woodlands areas.
The dangers
Azaleas contain substances called grayanotoxins that are present in all parts of the plant. Grayantoxins block normal function of the muscles in people and animals, including the heart, and can impair nerve function. Whilst rare – if ingested it is toxic to humans and animals.
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
Part of the Rhododendron family Yellow azalea or honeysuckle azalea is a bushy deciduous shrub that grows up to 4 metres high, with oblong leaves turning orange, purple and red in autumn and a bright display of bright yellow clustering flowers that emit a heady perfume.
Cotoneaster
Widely seen in woodland, scrub, hedgerows and quarries, and on railway banks, roadsides, sand dunes, cliffs, walls and waste ground, Cotoneaster is an invasive plant that forms a thick blanket of small leaves and red berries.
The dangers
If ingested in large amounts, all parts of the plant are toxic to humans, dogs, cats and horses. Whilst there are few reported cases of pets being poisoned from ingesting Cotoneaster, it should not be dismissed as danger as cyanogenic glycoside toxicity can occur. The berries are poisonous to humans, mostly causing gastric hypersensitivity if ingested.
- Do not eat any part of this plant
- Do not handle without protective clothing and gloves
What to look for
Cotoneaster is an erect deciduous shrub, with leaves of 1.5 – 2.5 cm long, small-leaved Cotoneaster is evergreen with very small leaves at 0.5 – 0.8cm long. The flowers are small, white or pink in the spring, followed by clusters of red/orange berries in the autumn.
Goat’s rue
Goats-rue is a herbaceous perennial in the legume family (Fabaceae), and gets its name from when it was given to nanny goats to increase their milk yield. Goat’s rue thrives in marshy fields, meadows, woodlands, sunny forest edges, semi shaded fields and along roadsides and stream banks.
The dangers
Goat’s rue is poisonous to livestock, especially when the seed pods are young. It produces a toxic alkaloid (galegine) that affects ruminants with the potential to induce a build-up of excess fluid in the lungs, cause blood pressure issues, paralysis and death. Poisoning to humans is very rare and there is to date no recordable evidence.
- Do not eat any part of this plant
What to look for
Stems that have leaves branching from both sides, with white and bluish to purplish pea-like blossoms flower in late May to June that continue until frost around November.
Conclusion
Being plant aware is vital for human, pet and animal safety when out and about. Education is key – knowing which ones to swerve past will reduce the number of casualties these toxic plants cause in the UK every year. If working in areas where these plants thrive, please be extremely cautious, wear protective clothing and avoid contact. As a rule – if in doubt, do not go near. Use our free identification tool if you’re unsure – send us some pictures and we’ll identify the plant for you.