Poisons, pains and healing with Rhus
This month we continue to chat about trees in the Rhus genus, recently re-named Searsia in Botanical science. In the May blog I mentioned that that they are part of the Mango Family (Anacardiaceae) and talked briefly about some of the medicinal and poisonous properties that members of this Family possess. This month I want to take the fascinating subject even further, of plants and their ability either to heal or cause pain, again concentrating on Rhus species.
For thousands of years, perhaps millions, people have been aware of the healing and poisonous properties of plants. The juices, sap extracts, bark infusions, leaf decoctions, fruit pulps, seed grindings, dehydrated pounding of roots (the list goes on!) have been used to treat all kinds of illnesses and afflictions to which humans are prone. Over the millennia we’ve also learned which plants will cause pain or irritation.
Worldwide, people have certainly been aware of, and made use of, Rhus species – that group of plants that we have categorised scientifically as either Rhus or Toxidendron. Just by looking at some of the common names they have been given, one is able to get a pretty good idea of their chemical qualities, and whether they are to be avoided. Poison Ivy, Atlantic Poison Oak, Chinese Varnish Tree, Lacquer tree and Wax Tree are good examples of this. Most Rhus contain strong chemicals that are toxic to humans, or at very least cause some kind of reaction on any human skin that touches the plant. Our South African species that were classified as Rhus do not, in general, cause serious skin irritations and this is probably one of the reasons they are not as well known as their international cousins. Although, evidence shows that our humble Gewone Taaibos (Common Tough Bush – Afrikaans for Rhus pyriodes) has made its uncomfortable mark on many human fingers, arms and legs. This chemical reaction was acknowledged by one of its earliest English names, Fire-thorn Currant.
Searsia pyroides flower and fruit Searsia pyroides
ART by Joan van Gogh
While many of the common names above warn us to stay away, the fascinating truth is that there are medicinal qualities in these Rhus plants that can be used to cure the very reactions that their poisons cause. For instance one of the most famous Homeopathic treatments is called Rhus Tox, and is used for treating extreme, sharp burning pain, redness and acute inflammation of the skin. Here’s the interesting thing – this remedy is made from Poison Ivy, Rhus toxicondendron, a plant that inflicts the same pain as that which Rhus Tox cures.
To return to Rhus pyroides – the Common Currant Rhus – it is in fact a bit of a wonder tree. For centuries Africans have used remedies made from various tree-parts to treat epilepsy. Recently two bioflavonoids were identified in its structure and flavonoids have specific healing properties. Some of these include protection of the human vascular system, as well as having active anti-inflammatory, anti-tumor and anti-hypertension agents. Scientific evidence is now indicating that at least some of the ancient pharmacology was valid.
The above are some of the reasons why I remain intrigued by the Rhus tree species. In June I acknowledged the fact that their flowers are not spectacular, and their fruits are small and rather sour. Even so, I believe that if you start trying to identify the Rhus species near you, you will find that you have invested in a life-time of added interest in all your road and wildlife travels.