by Rachel Burrows, Master Gardener

Plants are unable to hide or run away when faced with danger such as being eaten by a hungry rabbit. However some plants are toxic and can cause anything from mild discomfort to fatal consequences. Many of them are lovely to look at but it is wise to know which are poisonous especially if you have young children or pets.

Castor Bean Plant (Ricinus communis)

A friend phoned me and said that she had a fabulous plant with very unusual seed heads and would I like to take a look at it as she didn’t know what it was. Castor bean plants contain ricin, one of the most toxic substances known. The ricin is in the seeds which are covered with a prickly coating and are pretty shade of dark red. If the seed is swallowed whole without damaging the seed coat it will likely pass through the digestive system harmlessly. However, if it is chewed and swallowed the ricin will be absorbed within minutes and is usually fatal. One seed is enough for a deadly dose for a child and about four for an adult. My friend was very surprised and agreed to dig the plant put of her garden and dispose of it safely. These plants are often grown for their ornamental properties as they are tall and a lovely colour.

Yews (Taxus)

Again, another popular plant for hedges and often seen in gardens. The entire shrub is poisonous except for the red flesh of the berries. The oval, black seeds within the berries are highly toxic and can be fatal within a few hours of eating as few as 3 seeds. The toxin in yews is taxine which is a cardiac suppressant. I grew up on a farm and we all knew not to have yews in fields with livestock.

Rhododendron

Not so hardy and a little harder to grow in this area but very common further south and in parts of England. All parts of the rhododendron are poisonous, even honey produced form the shrubs is poisonous.

Mountain Laurel (Kalmia latifolia)

This shrub is a close relative to Mountain Laurel and all the green parts, twigs, blooms and pollen are toxic. It’s blooms are gorgeous but beware!

Lily of the Valley (Convalliaria majalis)

Lily of the Valley is valued for its lovely perfume and as a ground cover, although some people see it as a menace as it does spread quickly. The entire plant is poisonous and causes the heart’s contractions to intensify.

Monkshood (Aconitum)

This is a stunning, tall perennial which blooms late in the season with striking purple flowers. All parts of the plant especially the roots and seeds are extremely poisonous. Eating as little as 1 gram may cause death. Even the sap can cause fingers to become numb.

Delphinium

Another lovely and showy perennial, but all parts of the plant are poisonous, especially the seeds. Death can be caused in as little as 6 hours.

Foxglove (Digitalis purpurea)

Another commonly grown plant that produces the well known heart medication. However, the whole plant is poisonous and the toxin is deadly in high doses.

There are several other poisonous plants that you might want to think twice about before bringing them into your garden. Be aware of their deadly potential especially if you have young children or pets. By all means grow them if you love them, just be careful.

Did you know? There’s a garden in England dedicated to poisonous plants? Take a tour – virtually..

For further information and pictures of other poisonous garden, wild and house plants check out these websites

Ontario Poison Centre – Plants

Good Housekeeping List of Poisonous Plants Around the Home

Landscape Ontario – List of Poisonous Plants