| Over 80,000 plants species are in use throughout the world. Amongst them, medicinal plants continue to play a central role in the healthcare system of large proportions of the world's population. This is particularly true in developing countries like the ones in Africa, where herbal medicine has a long and uninterrupted history of use. It forms the basis of all medicine-conventional drugs, homeopathic medicine, Chinese medicines, etc. Recognition and scientific development of the medicinal and economic benefits of these plants are on the increase in both developing and industrialized nations.In Asia, the practice of herbal medicine is extremely well established and documented. As a result, most of the medicinal plants with international recognition such as Ginkgo biloba, Ziziphus jujuba and Z. mauritiana come from this region, particularly from China and India. In recent years, for example, the Chinese plant Artemisia annua L., has become the essential ingredient in a new generation of anti-malaria drugs. The plant is now being grown in East African countries to supply pharmaceutical manufacturers in Europe. In Europe and North America, the use of herbal medicine is increasing fast, especially for correcting imbalances caused by modern diets and lifestyle.Use of plants for medicinal remedies is an integral part of the cultural life of the people of Africa as well, and this is unlikely to change in the years to come. In Africa, traditional medicine is a socio-economic and socio-cultural heritage, servicing over 80% of the populations. They are being used to fight illness and maintain health. For instance, indigenous San have used Harpagophytum procumbens (Devil's Claw tubers) medicinally for centuries, which is now being exported to Europe, in the treatment of mainly arthritis, arteriosclerosis and rheumatism. Furthermore, drugs to fight other life-threatening diseases like diabetes, cancer, HIV and diarrhea-and even substances to protect crops from slugs-are being developed from plants, microorganisms, amoeba and other species from African countries such as Egypt, Somalia, Libya and Gambia. Using available literature from recent journal articles, books and other various publications, this study particularly focused on the immense ethno-medicinal importance of African plants namely Sclerocarya birrea, Ziziphus mucronata and Faidherbia albida. In addition, their domestication potential, more especially in areas where they are underutilized, as well as their current economic importance in the region is explored, for instance, in relation to pastoral farming as in the case of F. albida. The multiple uses associated with most parts of S. birrea make it one of Africa's most valuable trees. This includes its contribution towards health, nutrition and food security. Archaeological evidence indicate that it was consumed by humans since 9,000 BC. S. birrea fruits can be eaten fresh, squeezed to make juice, brewed in traditional beer, or even used to make jam and jelly. The barks, seeds, roots and leaves are exploited for traditional medicinal purposes to treat diverse ailments like hepatitis and rheumatism. S. birrea has acquired significant commercial value since its fruits and other products entered the local, regional and international trade in Southern Africa. The accumulated knowledge and skills relevant in establishing and commercializing S. birrea can therefore guide the same in areas where S. birrea remains undomesticated or underutilized.Not only is traditional medicine popular and accepted, but also in some areas it is the only system available. Western medicine is costly and often inaccessible. In Africa, rural people depend heavily, if not exclusively, on indigenous healthcare knowledge to meet their medical needs from plants like the underutilized Ziziphus species. However, in terms of abundance and economic value, Z.jujuba and Z. mauritiana are currently the most important, especially in China and India. The study examined a related common species widely distributed in Africa, Z. mucronata, whose economic value is not yet explored. Local people in various African countries use its different parts to cure numerous diseases, many of which are similar to those treated with Z. jujuba and Z. mauritiana.On the other hand, other medicinal plants like F. albida provide additional essential benefits to communities. F. albida is an ideal agroforestry tree commonly intercropped with annual crops like millet and groundnuts in the dry and densely populated areas of Africa. With its peculiar reverse phenology, it makes growth demands at a different time from that of crops. In addition, it deposits great amount of organic fertilizer on food crops. Leaves entering soils are comparable to fertilization of almost 50 ton ha-1 year-1 of manure in dense stands of 50 large trees per ha. These nutrients help maximize agricultural production and reduce the need for a fallow period on poorer soils. Research has shown that millet grown under F. albida yielded 2.5 and 3.4 fold increases in grain and protein, respectively. Animals eat pods which contain mean crude protein (20.63%) and carbohydrate (40.1%) in seed. Moreover, the continued existence of F. albida in agroforestry parklands as in Ethiopia and Mali signifies the successfulness of traditional conservation measures. To ensure food security, which still remain a major challenge in Sub-Sahara, and concurrently minimize environmental degradation, promotion of agroforestry that specifically involves indigenous trees is crucial.For comparison's sake, the immeasurable significance of G. biloba and M. glyptostroboides, both found in China, were also covered. At over 200 million years, G. biloba is the oldest tree on earth. It is described as a "living fossil" since all of its relatives died out during the last glacial period. G. biloba is listed as a rare species in the 2010 International Union for the Conservation of Nature and Natural Resources (IUCN) red list of threatened plants and is native to Eastern China. At present, this species has also been extensively cultivated in Europe, Australia, Japan, Korea and the U.S.A, because of its health-promoting properties. Medicinal extracts are made from the dried leaves of the tree and have been used for 5,000 years in traditional Chinese medicine for various purposes. In China's mainland and Japan, preparations incorporating G. biloba are used in the treatment of cough, age-related physical and mental deterioration, dementia, asthma and even alcohol abuse. The standardized extract of this plant, called G. biloba extract-EGb 761-was until recently the most prescribed phytomedicine in England and France, to improve memory, to treat among others depression, dizziness, tinnitus, vertigo and intellectual deficit.The 1941 description of M. glyptostroboides from fossil records found in Japan, followed by the discovery of its live trees in the same year in China was one of the greatest botanical discoveries of the 20th century. This fast growing tree is native in south-central China where approximately 5396 of them exist either as scattered individual trees or in populations. M. glyptostroboides is not likely to go extinct as it is both widely planted in China and protected by the law. It has been introduced to the U.S.A in 1948 and later to 53 other countries on almost every continent. As potentially the most successfully recovered threatened wild species today, with many more individuals and a much wider distribution, M. glyptostroboides has become a popular ornamental plant.In general, the various widespread uses of S. birrea, Z. mucronata, F. albida, G. biloba and M. glyptostroboides have regrettably accelerated pressure on their wild plant populations. For example, even though M. glyptostroboides will continue to exist in yards, parks and on roadsides all over China, the M. glyptostroboides forest ecosystem could disappear when its mature trees die. This is because of the demand for seedlings which drives cone collection to the point that natural reproduction is no longer occurring in its forests. Furthermore, S. birrea is vulnerable to loss of genetic variability due to its dioecious nature which sometimes results in male trees being selectively removed and used as fuelwood. Another significant conservation concern is the displacement of S. birrea from populations of natural seed dispersers. Fortunately, the need to conserve S. birrea has been recognized over the past decade and one way to achieve this is through domestication. Additionally, from a research and development point of view, many Ziziphus species, Z. mucronata included, have not received any major emphasis from governments and as such, they remain underutilized. This needs to be improved, so, their wide adoption and hence sustainable exploitation is encouraged.The great biodiversity in unique African environments has provided indigenous cultures with a diverse range of plants and as a result a wealth of traditional knowledge about the use of plants for medicinal purposes. Nonetheless knowledge of these African species is still limited in other countries such as China. This study is expected to contribute toward bridging the existing information gap with respect to knowledge on the specified tree species in both Africa and China. |
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