Wednesday, 9 March 2011

Danger in the Garden


POISONOUS PLANTS

Last week I ran over those plants to grow for a healthy lifestyle including superfoods as well as seasonal fruit and vegetables to maintain peak health all year round. The garden and allotment has the capabilities of providing us with delicious and very nutritional foods, but on the other side of the fence lurks an extremely dangerous place for the unwary.
Life on this planet has evolved as one species feeds on another, whether it is at virus level, fungus, bacteria, animal or plant. To hang onto life for as long as possible plants animals and even microbes have all developed some means of resisting becoming someone’s next meal ticket. Microbes play the numbers game with an ability to grow and mutate at an alarming speed. Animals have developed an ability for camouflage, or can run at great speed, or have horns, claws and teeth, poisonous fangs or just great strength.
Plants can’t run, shout, fight, have no claws or teeth, but they have just as much a desire for survival so, as well as thorns, they have developed a massive array of poisons in roots, bark, leaves, stems, seeds and flowers to deter predators from eating them.
We are all mostly familiar with the obvious ones such as laburnum seeds, foxgloves and giant hogweed, and we have all been stung by nettles, but when I started to look into other garden plants that could be added to the poisonous list, it amazed me that there was so many.

Danger lurks in every garden

Poisonous plants are very common in most gardens, e.g. rhododendrons, narcissi and aconites. Council parks, and shopping centres are also landscaped with a wide range of poisonous plants including laurel, snowberry, azaleas and yew trees.
Even in the home we grow hyacinths, poinsettias and oleanders which all contain toxins.
Now just in case anyone is feeling a bit off, and before you chop down the rhododendrons can we keep the dangers in perspective!
Most poisonous plants are so bitter or foul tasting that they would not normally be eaten, and some require very large quantities to be ingested before reaching a critical dose.
Apples are one of the most popular fruits, and many people just swallow the seeds. The seeds contain cyanogenic glycosides, a cyanide compound that could be fatal in high enough concentrations.  However we would need to consume massive amounts of apples and crushing the seeds before we swallow them. Some of this toxin is broken down in our digestive processes quite naturally. Other fruits in the same group also possess similar poisons in the seeds and kernels such as cherries and apricots.
The leaves of rhubarb are very toxic containing oxalic acid, but nobody would ever want to eat them, so there is little problem.
Then there is the humble spud, a member of the solanaceae family, which has some very poisonous relatives such as the deadly nightshade and datura, also known as Angel Trumpets. Tomatoes, peppers and tobacco also belong to this group, and are known to possess a wide range of alkaloids which can be addictively desirable e.g. tobacco, or fatal e.g. belladonna and datura containing tropane.
Although the potato is a staple food, the leaves, stems, seeds and those tubers that have turned green on exposure to light all contain the toxin glycoalkaloid solanine. This toxin is also present in tomato leaves, stems and unripe fruits.

Fatal Flowers

Angel Trumpets, Datura stramonium is used in summer beds and borders. It has large highly scented trumpet flowers that are at their best at night. Every part of the plant is toxic. South American native Indians use it as a drug because of its hypnotic and hallucinogenic affects. In the wrong dose this exotic plant can be fatal. Monkshood, a pretty blue perennial plant is so toxic it has been used in the past to poison enemy water supplies, arrow heads and kill wolves and bears.
Rhododendrons, aconites, narcissi, foxgloves, autumn crocus, daphne, delphinium, and calla lily are all toxic if ingested.
The toxic house plants include hyacinths, poinsettias and dumb cane which can cause immobility of the mouth and tongue, great difficulty in breathing and asphyxiation.
Toxic weeds include hemlock containing alkaloids, deadly nightshade which contains the alkaloid atropine and giant hogweed whose sap is phototoxic and can cause a severe rash and blisters.

Toxic Trees

Apart from laburnum whose seeds are particularly poisonous, most other harmful trees mainly affect farm animals. Beech, chestnut and especially oak can have an accumulative poisonous affect if normal grazing meadows are poor and trees are nearby. Some animals can become addicted to acorns or young fresh leaves in spring which are all high in tannic acid. Small quantities are fine but eating these in quantities should be positively discouraged.
The yew tree
The most toxic tree in UK has to be the yew tree. Its toxins have protected it so well from foraging predators that it can last for hundreds of years. It can also regrow from basal suckers so the original tree could have originated up to 4000 years ago. The yew was revered as a sacred tree by Greeks, Romans, North American Indians and in UK by the Celts and Druids. It was associated with immortality, rebirth, protection from evil and access to the underworld.
The growth is very slow so it produces a very fine grain making it perfect for tools, spears and hunting bows. Its extensive use in the middle ages for the long bow caused its demise as a dominant woodland tree across Europe. As every part of the tree is extremely poisonous, except the fleshy aril around the seed, it was used to add poison to the tips of arrows.
The Druids would plant them in circles to protect sacred ground and monks would use them to mark and protect the routes of their pilgrimages. Many very old yews survive in churchyards as the sacred ground is protected.
The oldest tree in Europe is the Fortingall yew near Loch Tay at over 3000 years old.
The stems, leaves and seeds contain the toxic alkaloid taxine.
Several suicides have been reported by people eating the leaves. On the positive side taxol extracted from the leaves can be used as an anti cancer treatment as it stops cell mutation. Extracts from the fleshy aril around the seeds can be used as a diuretic and laxative.

The above list is only a small sample of a long list of garden plants with toxic properties. Never take any risk with some berry that may look quite attractive and edible. Sometimes even a small amount may not be fatal, but could cause skin rashes, sickness, and heart palpitations.


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