Traditional Methods of Conserving Medicinal Plants in Zimbabwe
Volume 2 Number 8 - July 1997
S. Mavi & S. Shava
The rural people who constitute the bulk of Zimbabwe's 10.4 million population are heavily dependent on the vegetation around them for fuelwood and for medicine. They are mainly subsistence farmers, and cannot afford alternative fuels, let alone the high prices of modern medicine. As a result vegetation is lost and environmental degradation takes place.
Major steps have been taken towards conserving the environment in Zimbabwe. They include: discouraging cutting down indigenous trees and encouraging the local people to plant fast-growing exotic and indigenous trees for domestic use, the inauguration of a national tree planting day and the creation of nature reserves. However, despite this intensified drive towards conservation, it is still difficult to prevent local people from destroying the plants around them.
The planting of fast-growing exotics is not a complete solution to the problem of environmental degradation, mainly because the locals still need indigenous plants as a source of medicine and for crafts such as carving. Local people do not approve of the planting of medicinal plants because of their belief that indigenous plants lose their curative properties when cultivated.
The local people are not likely to readily accept new doctrines thrust upon them in the form of modern environmental conservation strategies, which most of them do not understand. But something can be done however, in particular about the utilization of indigenous plants for medicinal purposes. For example, it is clear that certain conservation techniques are implicit in the traditional methods of obtaining medicines from plants.
This article discusses some of the conservation measures that have been applied by traditional herbalists in the past. They are grouped under two headings: traditional ways of collecting plant medicines, and plants protected or planted because they are associated with certain traditional beliefs.
Traditional Methods of Collecting Medicinal Plants Used by Herbalists
Collection of bark - It was traditionally believed that bark from a tree should only be collected for medicinal purposes from the east- and west-facing parts of the trunk. Bark taken from the north and south faces was believed to be ineffective for curative purposes. This method ensured that the plant, although ring-barked, was not killed and could be collected from again in the future.
Collection of roots - When collecting roots for medicinal use, not all the plant's roots were collected. The plant could therefore still feed from its remaining roots and survive. It was believed that if part of a plant was collected for medicinal use and as a result that plant perished, then the patient being treated using that medicine would also die.
Use of plants which have already been collected from - The collecting of bark, roots branches etc. from a plant that showed signs of having been collected from by another n'anga (traditional healer) was prohibited. It was believed that when a n'anga used a plant to treat a patient, the patient's disease was transferred into that plant. When another n'anga subsequently used the same plant to treat a patient, the disease of the previous patient would be transferred to the new patient. This belief ensured that the plant recovered from the effects of collection.
Use of annuals - Whenever a n'anga collected annuals for medicinal use they had to leave behind some individuals of the species at the collection site. It was believed that if a species was completely destroyed in a particular area, then the patient to whom the medicine from the species was administered would also die. By leaving behind some representatives of the collected species, localised rare species were protected from extinction.
Use of seeds - Seeds were rarely used for medicinal purposes. When they were used, it was usually as a lucky charm placed in a pocket or hung around the neck. This limited use of seeds allowed the perpetuation of plant species through seeding.
Plants protected or planted because they were associated with certain protective or evil properties
Kirkia acuminata Oliver
A truncheon from this species was specially propagated by every newly-married man to appease his ancestral spirits so that they would protect him from witchcraft and evil. It was believed the ancestral spirits would come to reside in the tree.
Trees of this genus were not cut down when clearing land for cultivation or constructing a home. They were believed to prevent people or a place from being struck by lightning, and thus it was an advantage to have them around the house. It is interesting to note that trees of this genus are used for the same purpose in other parts of Africa, such as Angola.
Euphorbia ingens Boiss.
This tree was believed to be capable of warding off lightning and so is not tampered with if found growing near the home. The plant was also grown on graves to prevent witches from exhuming the bodies of the deceased.
Oxytenanthera abyssinica (A. Rich.) Munro
As with Gardenia spp. and E. ingens, this species was grown around the house to protect it from lightning strikes.
Lonchocarpus capassa Rolfe
It is believed that this tree was used by witches for casting evil spells. It was also said to cause discord within the family if used as fuelwood. For these reasons the tree was never cut down or used as fuelwood.
In Botswana the belief version of L. capassa differs from the Zimbabwean one in that the tree is associated with the production of rain. This belief stems from the fact that this tree species is usually invaded in early summer (before the rains break) by an insect, a frog hopper, which feeds on the sap of the tree. Since the sap is very dilute in nutrients, the hoppers have to consume large quantities of it, passing out drops of water which then fall from the tree branches. Where the insects are very profuse on a tree, they release numerous drops of fluid, with the resulting effect looking like rain from the tree. When someone stands below that tree, they may get wet, hence the name 'rain tree'. It was believed that if anyone cut down this tree then no rain would fall on their fields. The whole area around Makarikari in Botswana is denuded of trees - except for the rain tree.
Psorospermum febrifugum Spach
As with 'rain tree' mentioned above, it was believed that, when used as fuelwood, this tree would bring about unrest within the family. It was therefore left untouched.
Pseudolachnostylis maprouneifolia Pax
This tree was believed to be used by witches for casting evil spells and it was therefore a taboo to use it for any purpose.
From the above discussion it is apparent that our ancestors in Zimbabwe did practice conservation, and that environment conservation is not a new concept to our local people. Some of the above practices are still carried out today. However many of them have fallen out of use, because of the mixing of cultures through migration and urbanization, which has resulted in the depreciation of local people's knowledge of their ancestors' beliefs and traditions. This is being aggravated by population pressure on the land, which has resulted in clearing of vast areas of vegetation to make way for cultivation and the construction of houses. Local people have always depended on nature and the land for their survival and it is difficult to convince them otherwise. They expect the land to permanently provide for all their needs without any reciprocal care by them. By the time they wake to realise the effects of their actions on the environment, they will have nothing left to salvage from it.
In spite of the difficulty of making people appreciate modern teachings on the need to conserve their environment, not all hope is lost. People have a tendency to understand and appreciate improvements that relate to their traditional ways of thinking, rather than newly-introduced ways of thinking that do not take into consideration their way of life. By reintroducing and trying to highlight the value of traditional conservation methods, some improvement can be made in the attitude of local people towards their environment.