One of the needs identified by participants of the workshop on an African Ethnobotany Network was for a review of past literature and themes that have been followed within African ethnobotanical work. This review of ethnobotanical studies in East and southern Africa is a first step in this process. Some literature is certainly left out: far too much valuable data is inaccessible as "grey literature". This needs to be rectified: first, through placement of copies in the AETFAT (Association for the Taxonomic Study of the Flora of Tropical Africa) library, and secondly, through publication of results of these studies in internationally refereed journals. It is hoped that network members from West Africa will follow the next AETFAT Congress with a review of West African (and particularly francophone) ethnobotanical literature. In this way, the African Ethnobotany Network can stimulate a coordinated approach which avoids research repetition, disseminates information and stimulates publication of research in international journals. At present, the only African regional initiatives which facilitate a coordinated approach to research are the NAPRECA (Natural Products Network for Eastern and Central Africa) group in East Africa and the Indigenous Plants Use Forum (IPUF) in South Africa.

As ethnobotanical research is at the interface between disciplines, it poses an interesting problem in terms of literature review. Significant contributions are made to this field of study by anthropologists, archaeologists, architects, chemists, linguists and naturalists as well as botanists. Ethnobotanical research in East and southern Africa could be divided into five main themes in roughly historical order:

(i) a focus, for more than a century, on recording vernacular names and uses;

(ii) nutritional and chemical analyses of edible and medicinal wild plants species. These were compiled in Watt and Breyer-Brandwijk's classic (1962) book on East and southern African medicinal plants and by Fox and Norwood-Young (1982) and Wehmeyer (1986) on edible plants for southern Africa and Fowden and Wolfe (1957), Imbamba's (1973), Miege and Miege (1979) and Kalenga Saka and Msonthi (1994) for East and south-central Africa;

(iii) the studies of the quantities of plant material used and/or frequnecy of use, starting with Quin's (1959) and Scudder's (1962) records of edible plant use, and then since the late 1970's, on measurement of wood use for fuel and building purposes ((Best, 1979; Whitlow, 1979; Gandar, 1983; Liengme, 1983; Erkiila and Siiskonen, 1990; Grundy, 1996; Grundy et al., 1993; Vermeulen, 1993, 1996) and on use of introduced Acacia species in the Fynbos biome (Azorin, 1992). The most comprehensive review of wood use is by Campbell and Mangomo (1994). Working in East Africa, novel methods have been used by Johns and Kokwaro (1991) and Johns et al. (1994) on food and medicinal plant use. A recent focus of quantitative has also been on human impacts (iv below) and on the ecological benefits from tree conservation, values and social importance of trees (see (v) below);

(iv) quantitiative studies on human impacts on plant resources, particularly those entering commercial trade, such as the impact of palm sap tapping (Cunningham, 1990a,b), the harvesting of aloe resins (Bond, 1983), craft materials (Cunningham and Milton, 1987; Cunningham, 1987, 1988b), traditional medicines (Cunningham, 1991, 1993), Phragmites australis reeds (Cunningham, 1985) and Cymbopogon thatching grass (Shackleton, 1990).

(v) most recently, valuation studies: of forest use in Kenya (Emerton, 1996) and woodlands in southern Africa (Campbell 1994; Campbell and Bradley, 1994; Lynam et al., 1994; Campbell et al., 1995; in press; Hot Springs Group, 1995; Shackleton, 1996).

Sclerocarya birrea (from/de: Flora of Tropical East Africa)

A remarkable issue is the continuity in use of a few key plant species across time (edible plants) or over large areas of their range in Africa (several medicinal species). Fruits and nuts of marula (Sclerocarya birrea, Anacardiaceae) and mangetti, Schinziophyton rautanenii (Euphorbiaceae) trees, seeds of the !nara melon (Acanthosicyos horrida, Cucurbitaceae), herbal tea from rooibos (Aspalathus linearis, Papilionaceae) and aromatic leaves of buchu (Agathosma betulina, Rutaceae) for example, were highly significant resources to hunter-gatherer peoples.All continue to be valued today. Several of these species have made the transition from wild species to crop plants. Conversely, since the late 19th century, new ornamental and industrial uses have been found for many indigenous plant species. As a result of this demand, several species have become the focus of "formal sector" national or international trade worth at least US$20 million/yr. In 1987 alone, 2000 tons of marula fruits were used in liqueur production.

Bark of medicinal plant species such as Prunus africana (Rosaceae) and Warburgia (W. salutaris in southern Africa, W. stuhlmannii and W. ugandensis in East Africa (Canellaceae)) selected for their active ingredients is very widespread. So are symbolic uses of selected species. The important symbolic triad of the colours red, white and black applies across southern and East Africa (Turner, 1967; Hammond-Tooke, 1989). The red and black seeds of Abrus precatorius or Afzelia quanzensis, feature widely in traditional medicines for this reason. Similarly, the tree species that provide the ingredients for the ikhubalo mix all have pink or red colour, as do many of the plant parts used in battle medicines. The remarkable white lignotubers of Synaptolepis kirkii (Thymelaeaceae) and leaves and twigs of the resurrection plant Myrothamnus flabellifolius (Myrothamnaceae) similarly have symbolic power, and are commonly used throughout southern and East Africa.

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In Loita, southwestern Kenya, the dried bark of Warbugia ugandensis (Canellaceae) is used as a remedy for coughs, fever and body pains.

2. Cross-reference records of vernacular-botanical names

Until the pioneering quantitative ethnobotanical studies by Scudder (1962) and Quin (1959), the major focus of ethnobotanical research in Africa was on recording vernacular names and plant uses. This theme has been followed for over 50 years in East Africa. In Kenya, by Greenway, 1940 (KiSwahili); Kokwaro, 1972 (Luo), Sangai, 1963 (Bondei, Shambaa and Zingua); Glover (1966) (Kipsigis); Glover et al. (1969) (Digo); Morgan (1980) (Turkana). More recently, Beentje (1994) compiled vernacular-botanical for trees, shrubs and lianas for Kenya, Bekele-Tesemma (1993) for Ethiopia and Mbuya et al. (1994) for Tanzania. The Luo-Botanical name dictionary (Kokwaro, 1972) is soon to be reprinted through collaboration between the Department of Botany, University of Nairobi and Professor T. Johns (CINE, MacDonald Campus of McGill University, Canada). Fewer published records are available for Uganda, the most comprehensive being in Eggeling and Dale (1952), Hamilton (1991) and Katende, Birnie and Tengas (1995).

In southern Africa, valuable contributions have been made through records of plant names in !Kung San (Story, 1958, Giess and Snyman (n.d), Khoekoe (Nama/Damara) (Eiseb, Giess and Haacke, 1991; van den Eyden, Vernemmen and van Damme, 1992), Shona (Wild, 1952), Sotho (Jacot Guillarmod, 1971), Swazi (Compton, 1966), Zulu (Bryant, 1908; Gerstner, 1938, 1939, 1941; Doke and Vilakazi, 1964), Venda (van Warmelo, 1937) and KwaNyama Owambo (Rodin, 1985) plant names. De Koning (1993) has produced a list of vernacular names of plants for Mozambique, based primarily on notes on plant specimens in the two major Mozambican herbaria. Le Roux (1971) lists local names of plants and some of their uses in Namibia, and Smith (1962) does the same for South African plants.

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3. Edible wild plants

The most recent review of edible plants (for sub-Saharan Africa) is that of Peters, O'Brien and Drummond (1992). Rammeloo and Walleyn (1993) review use of edible fungi of sub-Saharan Africa, and Pegler and Pierce (1981) document the edible mushrooms of Zambia. In East Africa, most ethnobotanical publications on edible plants are records of vernacular names and species eaten by people in Uganda (Bennett et al., 1965; Bukenya, 1994, 1996; Cunningham, 1992, Cunningham et al., 1993; Tallantire and Goode, 1975) and Kenya (Glover, Stewart and Gwynne, 1966b; Kabuye, 1986; Maundu, 1987; Morgan, 1981, Taylor, 1970; Wagner, 1970; Weiss, 1979), often with notes on most favoured species. Despite the widespread use of and trade in a wide diversity of edible fungi, very few studies are published on any aspect of this in Kenya (only Pegler and Rayner, 1969) or Uganda (Mukiibi, 1973; Oland and Stabursvik, 1970). At least three studies cover the interesting interface between food and medicine: Ochoki's (1981) study of plants eaten by pregnant or lactating mothers (with some records Kofi-Tsekpo's (1993) study of plants used in traditional soups and teas). This level of detail was not included in the review of edible plant use in eastern and southern Africa (Grivetti, 1981) or that by Peters and O'Brien (1981), which focussed on hominid food use. In contrast with the number of studies on home-gardens in Asia and Latin America, few studies of this have been done in East or southern Africa, one of the exceptions being Asfaw and Woldu's (1997) study of crop associations in Welayta and Gurgae home gardens in southern Ethiopia, which documents the extensive cultivation of Ensete ventricosum in this area.

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3.1 Nutritional values

Despite the change from a hunter-gatherer lifestyle to pastoralism or agriculture, hunting and gathering remain important to a high proportion of rural households in southern Africa (Campbell et al., 1991; Cunningham, 1988a; Malaisse and Parent, 1985; Ogle and Grivetti, 1985; Wilson, 1990). Starchy staple diets are frequently deficient in nicotinic acid, vitamin C, calcium and riboflavin, protein and caloric values. Several East African studies have taken nutritional values into account (Becker, 1984, 1986; Biellik and Henderson, 1980; Goode, 1989; Imbamba, 1973; Korte, 1969; Nestel, 1985; Muir, 1983; Mutiso, 1987) but nutritional analyses studies by Fowden and Wolfe (1957), Imbamba's (1973) and Miege and Miege (1979), and more recently Maundu and Ngugi (in print) are amongst the few studies in Kenya and Uganda which carried out nutritional analyses. Bush foods are known from several southern African studies to be a valuable source of these nutrients deficient in starchy staple diets, particularly nicotinic acid from wild spinaches (Lewis et al., 1968), Hennessy and Lewis, 1971; Santos-Oliviera and Carvalho, 1975), vitamin C from wild fruits (Quin, 1959; Wehmeyer, 1966) and protein from Sclerocarya birrea, Schinziophyton rautanenii and Tylosema esculenta seeds and edible insects (Quin, 1959).

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3.2 Variation in gathering patterns

Differences in climate, soil and vegetation type are reflected in significant differences in the availability and use of edible plants across Africa. Some bush foods are widely eaten, whilst other types of gathering characterise a particular biome. Vangueria infausta, Ximenia caffra and Sclerocarya birrea fruits, for example, are popular throughout the savanna woodlands of East and southern Africa (e.g., Fox and Norwood-Young, 1982; Johns, Mhoro and Sanaya, 1996; Peters, 1988; Quin, 1959). By contrast, gathering grass and Monsonia seed-stores of harvester ants is unique to the Desert biome (Malan and Owen-Smith, 1974; Steyn and Du Pisani, 1984). In Tanzania, Peters, Maguire and Box (1984) record the seasonality of edible wild foods and compare this to agricultural food production. Bush foods are of great importance to the rural poor living in the vast area of southern and East Africa covered by nutrient poor, drought susceptible sands of the coastalplain along the east coast (which stretches from Somalia to South Africa, the Namib coast to the west and the Kalahari sands region in the centre.

Wild species that were outstandingly important food sources developed a special place at the culture/nature interface across southern Africa. This is expressed in territorial rights, protection in customary law and the symbolic and religious significance of these key food sources today and in the past. Inherited rights by extended family groups (!hao-!nas) are attached to !nara melon patches (Acanthosicyos horridus) in the Khuiseb delta (Desert biome), for example (Budack, 1983; Dentlinger, 1977). Similarly, in the Kalahari savanna, mongongo nut (Schinziophyton rautanenii) groves are associated with the !Kung san family units, with permission asked if others want to collect from the grove (Lee, 1973). Amongst farming communities throughout southern Africa, private rights are also accorded to marula (Sclerocarya birrea) and other wild fruit trees in cleared fields or near to homesteads, whereas anyone can collect fruits from uncleared woodlands. Private rights are also given to individual palm-wine tappers in Hyphaene coriacea savanna on the sandy coastal plain of south-eastern Africa (Cunningham, 1990b).

The availability of bush foods varies considerably across the sub-continent. O'Brien (1988), documents the decline in woody edible plant diversity across the region from east to west. Her data show that species richness of woody edible plants was lowest in the desert, Nama-Karoo, Fynbos and central Kalahari region of the Savanna biome. The highest diversity of woody edible species occurs in the eastern escarpment and eastern seaboard of the Savanna biome. Differences in extent of use of wild spinach is also apparent in different lifestyles across southern Africa, with a greater diversity of species used by agricultural and agro-pastoral communities than by hunter-gatherers, with disturbed habitats created for these "weedy" species at cattle posts or in fallow fields.

The diversity in use of underground plant parts and seeds (as opposed to fleshy fruits) across southern Africa shows the opposite trend to that of woody edible plants. A low number of edible species with root, tuber, bulb or corms are gathered on the coastalplain of the moist east coast (Cunningham, 1985), while a high diversity are used in the Kalahari savanna region. O'Brien's analysis was based on the distribution maps for 264 woody edible species from Coates-Palgrave's (1977) book on trees of southern Africa. It should therefore not be taken in isolation as the dietary importance of non-woody edible species also needs to be taken into account. Underground bulbs, tubers, corms and stems provide an important source of gathered food in the biomes which O'Brien (1988) shows as low in woody edible species. The Asclepiadaceae (Brachystelma, Ceropegia, Duvalia, Fockea, Orbeopsis, Stapelia and Raphionacme), Curcurbitaceae (Acanthosicyos, Coccinia, Corallocarpus, Cucumis, Momordica, Trochomeria) and Iridaceae (Laperousia, Babiana) are particularly important in this regard (Story, 1958; Archer, 1990; Geiss and Snyman, n.d). In an area where 31 woody edible species are recorded in O'Brien's (1988) analysis for example, Giess and Snyman (n.d) recorded 101 edible plant species. Of particular botanical significance is the use of underground parts of 43 species in 15 families used by !Kung San people in the north western Kalahari. The "underground forests of Africa" described by Frank White (1976) form part of this food resource. The Kalahari savanna is a centre of diversity worldwide for plants with geoxylic suffrutices, large underground woody structures which White (1976) records having evolved independently in 31 families. Several of these "underground trees" are a source of fruits (Lannea, Landolphia, Salacia, Parinari, Diospyros, Eugenia). To a lesser extent this also applies to the Mozambique coastalplain (White, 1976) as well.

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3.3 Quantitative studies of edible plant use

Quantitative studies of bush foods ("veldkos") have been at three main levels. First, the nutritional analysis of more than 300 bush food species carried out over more than 20 yr by A.S. Wehmeyer and colleagues at the CSIR (Wehmeyer, 1966; 1986; Wehmeyer et al., 1969; van der Merwe et al., 1967) and studies from Tanzania (Sreeramulu, 1982) and Kenya (Imbamba, 1973). Second, quantitative analysis of the amounts of foods collected and eaten (e.g., Quin, 1959; Wilmsen, 1978). Thirdly, use of the 24-hour recall method used by Fleuret (1979a,b) in Tanzania.

Two seminal studies quantified the dietary importance of bush foods to rural people when most ethnobotanical work was at a descriptive stage. First, Quin's (1959) work with Pedi people in the northern Transvaal and second, Scudder's (1962) work on the ecology of Gwembe Tonga people in the Zambezi valley. Both are excellent examples of quantitative ethnobotanical work at a time when the emphasis was on descriptive studies. On their own, data on nutrient composition give little insight into the dietary importance of bush foods. Quin's (1959) study not only recorded the identity, cultural importance and nutrient composition of edible insects, cultivated and wild foods plants in the diet of Pedi people, but also the quantities consumed in a meal ration. These studies put analyses of nutrient composition into context through the meticulous records of recipes and quantities of different foods that formed the meal ration. Quin (1959) and Scudder (1962) also obtained records of the frequency with which different foods, including gathered bush foods were consumed. Many studies, including the classic work on Bemba agriculture in Zambia (Richards, 1939) illustrate the great importance of wild spinaches in the diet of rural people (e.g., Ogle et al., 1990; FAO, 1986). Popular wild spinaches used widely in southern Africa are Amaranthus species (A. hybridus, A. spinosus) (Amaranthaceae), Pentarrhinum insipidum (Asclepiadaceae), Cleome gynandra (Capparaceae), Corchorus species (C. tridens and C. trilocularis) (Tiliaceae) and the introduced Bidens pilosa (Asteraceae). Wild spinaches were similarly reported as the main side to porridge in savanna areas of Swaziland by 39% of 133 meals surveyed (Ogle and Grivetti, 1985). A similar situation applies on the Maputaland coastalplain (Cunningham, 1988a) and in Tanzania (Fleuret, 1979a), where wild plants appeared in 32% of all meals, and 81% of vegetable side dishes comprised wild species, and 17.7% of introduced or cultivated vegetables. Ironically, most of the plant species providing this nutritionally important food resource are considered useless weeds by commercial farmers. Commercial farmers also tend to clear all trees from fields. To subsistence farmers, however, edible-fruit bearing trees form a crucial part of the food production system. Many other wild fruit trees are also valued as food sources and conservation of favoured fruit, fodder or shade producing trees has been an important factor in maintaining woody plant cover in agricultural lands of communal areas in southern Africa (Cunningham, 1985; Campbell, 1986; Wilson, 1990). In future studies on the values of bush foods, it would be useful to:

(i) use dietary evaluation methods described by Fleuret (1979b) and suggested by Dufour and Teufel (1995);

(ii)take a coordinated approach and avoid repetition of costly nutrient analyses already carried out for many species in the East African region by researchers in other parts of Africa such as Wehmeyer (1966, 1986), Wehmeyer, Lee and Whiting (1969), FAO (1988), Kalenga Saka and Msonthi (1994) and Wickens (1995);

(iii) gather meal ration data, as on their own, data on nutrient composition give little insight into the dietary importance of bush foods, and;

(iv) compare these against Recommended Dietary Allowance (RDA) tables so that through these four steps, a more objective assessment of gathered foods in diet can be made.

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4. Plants for medicine

Western and traditional African medicine are based on very different and well documented views of health and disease. Traditional medicine takes a holistic approach where disease or misfortune result from an imbalance between the individual and the social environment (Berglund, 1976; Ngubane, 1977) while western biomedicine takes a technical and analytical approach. The belief that nothing happens by chance, but is subject to influence by others, whether people in the present or ancestral spirits, is central to this aspect of plant use (Berglund, 1976; Hammond-Tooke, 1989; Reynolds, 1996). Determining the root cause of an illness or of misfortune and guarding against them is the role of the diviner rather than the herbalist. Traditional midwives have a separate role again, using a wide range of herbs and playing an important role in home childbirth in southern Africa (Anderson and Staugard, 1986).

Many plant species have deep symbolic, religious or magical meaning to the majority of southern Africa's people. In the past and today, plants with symbolic value are used by diviners and shaman to control events by supernatural means. Many plant species also symbolise this bridge to supernatural power and their species specific use, frequently reflected in their names, is often widespread. To farmers and pastoralists it is important not only to attract rain, but also to drive away storms which could destroy crops or to protect homesteads against lightning strikes.

The cultural context of this use is very important due to its central role in people's lives. Diviners are called in dreams by ancestral spirits and play a crucial role society. This has been well described in detailed anthropological work (Berglund, 1976; Hammond-Tooke, 1981; Ngubane, 1977). Misunderstanding of divining, which was equated with witchcraft, and legislation against it has not diminished the role of diviners in rural and urban society, particularly in time of conflict, social upheaval or uncertainty when it is important to draw on supernatural power.

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4.1 Eastern African medicinal plants

In Kenya records have been made of use of herbal medicines by Masai and Kipsigis communities (Glover, Stewart and Gwynne, 1966), Marakwet (Lindsay, 1978) and Turkana people (Bennett, 1996), people in Machakos district (Maundu, 1987) and around Arabuko Sokoke forest (Lukandu, 1991). Hedberg et al. (1982, 1983a,b) have produced a detailed inventory of medicinal plant use in Tanzania and Johns et al. (1994) of herbal remedies used by the Batemi people, Ngorogoro district, Tanzania. Records of medicinal plant uses for the entire East African region, compiled from East African herbarium records and personal research have been published by Kokwaro (1976). Few quantitative ethnobotanical studies have been done of medicinal plant use (notable exception are Johns, Kokwaro and Kimanani, 1990 and Johns et al., 1994). However, the Kenya Medical Research Institute (KEMRI) have an active programme analysing active ingredients of medicinal plants. They have also developed a medicinal plants database at the KEMRI Traditional Medicine and Drugs Research Centre, Nairobi. KEMRI have a very active programme studying active ingredients of medicinal plants (e.g., Kofi-Tsekpo, 1993) and have a programme developing commercial products, including an anti-malarial from the introduced tree species, Azadirachta indica. The Natural Products Network for Eastern and Central Africa (NAPRECA) is an active network which provides an excellent regular review of phytochemical studies of African plant species based on current literature.

Studies of medicinal plant use which cover a large portion of Uganda have been done over the past decade by the Natural Chemotherapeutics Research Laboratory (NCRL) in Kampala, but are unpublished due to concerns about intellectual property rights (IPR) issues. Medicinal plant uses are also recorded by Anokbonggo (1972, 1974), Ogwal-Okeng (1990), Origa et al. (1995) for Rwenzori Mountains National Park and in the current studies by Oryema (1996) in Erute county, Lira district.

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4.2 Southern African medicinal plants

Since the publication of Watt and Breyer-Brandwijk's (1962) seminal work, uses of southern African medicinal plants have been documented or reviewed by Gelfand et al. (1985) for Zimbabwe, Jansen and Mendes (1983, 1984, 1990) for Mozambique, Hedberg and Staugard (1989) in Botswana and Hutchings et al. (1996) for South Africa. Herbal remedies are widely used in southern Africa. Use also reflects distinct cultural preferences. In the Cape Fynbos region, Ferreira (1987) found that 88% of elderly coloured people used boererate ("home remedies"), primarily bossiesmiddels from aromatic Fynbos plants such as Salvia africana-coerulea (Lamiaceae) or Pelargonium antidysentericum tubers from the Nama Karoo. By contrast, most migrants to the Fynbos today are from the summer rainfall region. This is reflected in the species traded from the summer rainfall region or harvested from remnant Afromontane forests on Table Mountain.

The use of medicinal plants in traditional veterinary practice in Africa has recently been reviewd by Bizimana (1994), including many species used in East and southern Africa.

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4.3 Medicinal plants in trade

Studies of East African medicinal plants in local or international trade has been a gap in the past (exceptions being trade records for aloe resins (mainly Aloe secundiflora, 5-73 tons/yr to EU countries, Oldfield, 1993) and Prunus africana bark trade to France (Cunningham and Mbenkum, 1993). The need for additional work is being addressed by the TRAFFIC East/Southern Africa study on medicinal plant and animal parts in trade, coordinated by Nina Marshall, which covers 19 countries. This will build on earlier surveys of medicinal plants sold in local markets such as that of Kloos (1976) in Ethiopia.

Trade in traditional medicines is a multi-million rand "hidden economy" in southern Africa, where a high level of urbanisation generates high demand for traditional medicines, particularly to mining towns or large urban centres. There is also a significant export trade in Harpagophytum tubers from Namibia and Botswana to Europe (Nott, 1986). A preliminary survey of medicinal plants sold in markets in Zimbabwe, Zambia, Swaziland, Mozambique and a detailed survey of medicinal plants in trade in South Africa has been completed by Cunningham (1988, 1990, 1991, 1993) and Williams (1996). Over 400 indigenous plant species and 20 exotic species are commercially sold for this purpose in Natal, South Africa (Cunningham, 1991) and many more species are in use (Hutchings et al., 1996). High volumes traded also reflect the value placed on traditional medicines. In Soweto, Holdstock (1978) considered 80-85% of people in Soweto consult traditional practitioners. In Umlazi, one of the largest "townships" in the Durban area, 30% of a random sample of residents had used the highly toxic medicinal plant Callilepis laureola (impila) (Wainwright et al., 1977), by no means the most popular species sold in KwaZulu/Natal. Use of medicinal plants is even higher in rural areas in Natal as all respondents interviewed in a random sample in the Estcourt area using medicinal plants (Ellis 1986).

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4.4 Future directions: medicinal plants and health care

Based on studies elsewhere in Africa, Le Grand and Wondergem (1989), Green (1994) and Abdool Karim, Ziqubu-Page and Arendse (1994) all present reasons why research on the medicinal values of plants would seem to be a good idea:

• to achieve local community or national self-sufficiency in health care through promotion of locally available and culturally acceptable herbal medicines;
• to reduce over consumption and or abuse of pharmaceutical drugs and encourage more rational drug use through promotion of herbal drugs as a safer alternative. This requires that health care personnel recognise how and what people use traditionally. Also required are studies of cases where people use modern pharmaceuticals in a traditional way;
• to reduce national dependence on costly, and usually imported pharmaceuticals;
• to record toxic traditional medicines so that traditional healers might be persuaded to substitute safer plants or reduce quantities administered; and finally,
• to find and promote safe and effective traditional medicines for common illnesses such as childhood diarrhoea.

Although traditional healers are recognised in programmes such as THETA (Traditional and Modern Health Practitioners Together Against AIDS) in Uganda and ZINATHA (Zimbabwe National Traditional Healers Association) in Zimbabwe, and African universities, public and private institutions are involved in traditional medicines research, progress has been very slow in achieving the above goals.

Both Le Grand and Wondergem (1989) and more recently, Green (1994), point out that despite the scientific relevance of the clinic-oriented approach and research studies on the scientific validation of herbal drugs, these has made little contribution towards practical implementation in public health or improved use of herbal medicines in health care. In Ghana, after 15 years of research, no plants had been recommended for use. Tanzania and Thailand presented a similar situation, with clinical research in Thailand only completed for two of the five plant species under investigation since 1985 and lack of official promotion of any herbal medicines in Tanzania after more than 10 years of research at the Department of Traditional Medicine, Muhumbili Medical Centre in Dar-es-Salaam (Le Grand and Wondergem, 1989; Green, 1994). Two main reasons are given for this failure:

(i) the high cost (in terms of both time and money) of scientific validation of even a single herbal medicine. As a result, few results can be expected, despite great expectations that are raised;

(ii) a low level of co-ordination amongst the many interests involved in laboratory studies of medicinal plants. Le Grand and Wondergem (1989) suggest that this includes a greater interest amongst scientists in the scientific importance of these studies, rather than in priorities that might exist at the lowest levels of health care delivery and that no national guidelines or priorities exist for researchers in this field.

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5. Fuelwood and charcoal

Popularised as the "poor man's energy crisis" in the late 1970's, studies on fuelwood consumption and use are some of the early examples of quantitative ethnobotanical work related to plant use and resource management. The most comprehensive review of policies and literature is the book by Leach and Mearns (1988). In East Africa, studies on rural fuelwood use have been done in Samburu, Kenya (Perlov, 1984) and South Turkana (Ellis et al., 1984). In southern Africa fuelwood gathered from forest, woodland and exotic plantations accounts for 51% of the domestic energy use in South Africa (Basson 1987) and is the biggest consumption of plant biomass, with rates varying between 0,27 to 1,12 tons/capita/yr (Gandar 1983).

Fuelwood use has also been the focus of some major programmes such as the Beijer Institute/Kenya Woodfuel Development Programme (Chavangi, Engelhard and Jones, 1985) and the UNDP/World Bank (1987) Kenya urban woodfuel development programme. Data from the 1991 Ugandan Population and Housing Census showed that 72.3% of households in Kampala cooked with charcoal, 11.2% with fuelwood, only 9.9% with electricity or 4.9% with paraffin. Although not quantified, there has certainly been a massive increase in the marketing of charcoal along many major transport routes in East and Central Africa in recent years. With high rates of urban population growth (Kampala, 6-7% per yr; Durban, 10% per yr), and the consequent demand for fuel from bakeries, brick-makers and urban household use, this is likely to continue in the foreseeable future. The most recent, detailed study of fuelwood use in East Africa has recently (November 1996) been completed in Uganda for the National Biomass Study of the Forest Department, Kampala by a team of Ugandan and British consultants working for Energy for Sustainable Development (ESD). This concentrated on wood use for energy (fuelwood and charcoal), showing that Kampala consumes more than half the charcoal used in Uganda, with more than a third of this coming from savanna areas.

In Kenya, mangroves are a favoured source of charcoal. Until a ban was instituted in the early 1970's, large quantities of charcoal were exported monthly to the Middle-East, much of this from mangroves. A major consumer of mangrove trees has been the company Kenya Calcium Products Ltd (KCP)., situated at Waa, which produces lime from coral blocks. Charcoal is the only source of energy used to heat the lime kilns. In 1992, seventy percent of this charcoal was from mangrove wood, and most (75%) of fuelwood for KCP was obtained from the Forest Department (Hirsch and Mauser, 1992). Hirsch and Mauser (1992) estimated that 19,000 m3 of mangrove wood, and most (75%) of fuelwood for KCP was obtained from the Forest Department (Hirsch and Mauser, 1992). Hirsch and Mauser (1992) estimated that 19,000 m3 of mangrove wood was consumed annually for this purpose.

Charcoal will continue to be a major source of household energy in East and much of southern Africa in the future. What is changing, however, is source of supply, with a shift towards on-farm production. Around Nairobi, for example, 50% of all charcoal is produced from commercial trees grown on high-value farmland (National Biomass Study, 1996). In densely populated western Uganda, cultivated trees (e.g., Eucalyptus (58%) and black wattle (Acacia mearnsii (73%)) are the major sources of fuelwood (Wandera, in prep.). A survey around Bwindi Impenetrable National Park similarly showed that only 7.5% proportion of respondents in a survey of 120 respondents had obtained fuelwood from indigenous forest (Kanongo, 1990).

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6. Plants for fencing and housing

The influence of climate on lifestyle is also reflected in the diversity ofarchitectural styles and settlement patterns in Africa. Nomadic architectural styles used by pastoralists of North and East Africa have been recently reviewed by Prussin (1995), including some ethnobotanical information on Borana, Rendille and Somali plant use for crafts and housing construction. Acacia species (A arabica, A. bussei, A. setal, A. nilotica, A raddiana, A. tortilis) are a major resource for this purpose. In East Africa, Heine and Brezinger (1988) document plant use by the Borana pastoralists and Smith, Meredith and Johns (1996) by Batemi people in Ngorogoro district, Tanzania, including the use of building materials. In the arid Desert biome of southern Africa, homes of =Aonin (Topnaar) and Dama Nama communities are placed along major river valleys such as the !Khuiseb and Ugab ephemeral river courses. Houses are still made of slabs of Faidherbia albida bark over a wooden framework, but corrugated iron sheets are increasingly replacing stone or bark as construction materials (Du Pisani, 1978). Further south in the Nama Karoo, where rainfall is higher and sedges are more readily available along river valleys, unique portable matjieshuise of sedges (Scirpus inanis and S. dioecus) over a framework of curved branches, usually cut from Ziziphus mucronata (Archer, 1989, 1990). "Mobile" matjieshuise are similar to Khoikhoi pastoralist houses encountered in the Fynbos and Karoo biomes by colonial explorers such as WilliamBurchell, representing an architectural style little changed over 2000 yr. Today, however, though their form and framework are often the same, Scirpus sedge mats are being replaced by plastic, canvas or sacking. The volume of timber material used in this form of construction was low, due to the need for mobility in the seasonal movements after good pasture. Low levels of wood use were also a feature of traditional architecture of the Grassland biome which covers the highland plateau of southern Africa. Possibly because of the problems posed by limited fuel or construction timber, the grassland biome was not settled at all by pioneer agriculturalists of the first millennium and it was only in the second millennium when these farmers had built up large herds of livestock that they moved into the Grassland biome, constructing houses of stone in villages of up to 1500 people (Hall, 1987). As an alternative to stone, both Zulu and Swazi people developed a specialist architectural style in these grassland areas described by Knuffel (1973) which minimises wood use and maximises use of grass.

Growth form of mature, medium-sized and young Juniperus procera trees. (From: Noad, T.C. & A. Birnie (1989): Trees of Kenya, Nairobi)

By comparison to the Grassland biome, the Savanna biome was an excellent source of timber and thatch. In addition, the settled lifestyle of agro-pastoralists gave greater scope for a range of architectural styles. These also reflect cultural differences in use of space, an important aspect of traditional building documented for Himba-Herero homes in the Desert biome by Jacobsen (1988) and Owambo homesteads in mopane savanna (Mills, 1984). Plants used in traditional architecture are documented for Tsonga (Liengme, 1983), Tembe-Thonga (Cunningham and Gwala, 1986), KwaNyama Owambo (Rodin, 1985), Tswana (van Voorthuisen and Odell, 1976), Cape Nguni (Shaw and van Warmelo, 1972) and Zulu (Gandar, 1984) hut construction. Building styles and the materials used reflect cultural diversity as well as vegetation change. Vegetation changes across the Maputaland coastalplain in Natal, for example were reflected in building style. In the Sand forest ecological zone, 56% of homes were constructed with woven hardwood laths, 2000-3000 laths per home. By contrast, Phragmites australis reeds were used for wall construction 59-90% of homes in three other ecological zones and only 5-35% had lath woven walls (Cunningham, 1985).

Wood consumption for building varies considerably with traditional building style and the availability of materials. The most comprehensive studies of wood use in savanna woodlands have been done in Zimbabwe (Campbell and Mangomo, 1994; Grundy, 1996; Grundy and Campbell, 1993; Grundy et al., 1993; Vermeulen, 1993, 1996; Vermeulen and Campbell, in press). One of the few studies which has calculated wood use for building poles in East Africa is the study by Howard (1991) for the Bwamba and Bajonjo counties in western Uganda. Population densities in the area are high, while land-holdings are small in these intensively cultivated areas. In Bwamba, Howard (1991) calculated on the basis of a fuelwood consumption rate of 1.24 m3/person/yr and a building pole requirement of 0.27 m3/household/yr (0.038 m3/person/yr) that the 121,600 people (17,000 households) would require about 151,000 m3 of fuelwood and 4,600 m3 building poles every year.

The spectacular traditional Owambo building style in Namibia requires more wood than any other form of traditional construction in southern or central Africa. A recent study of wood use in a homestead in northern Namibia showed that a single palisade fence, 302 m long surrounding the main homestead was made of 7,700 poles. The entire homestead required the removal of more than 100 m3 of construction wood from surrounding woodland. Most of the wood (43 m3) is used for palisade fencing, primarily from Colophospermum mopane and Combretum trees (Erkiila and Siiskonen, 1992). By comparison, the mean timber volume of Tsonga huts in mopane savanna in the northern Transvaal was 1.22 m3 for round huts and 1.86 m3 for square huts (Liengme, 1983). Erkiila and Siiskonen (1992) calculated that wood use for constructing an Owambo homestead would require 15 m3/household/yr. This is five times more wood than the 3.02 m3/household/yr used for construction purposes in woodland in Zimbabwe (Grundy et al., in press).

In East Africa, Thomson and Ochieng (1993) studied forest use in Shimba Hills, Kenya and Thomson (1993) recorded Juniperus procera exploitation for construction posts from the South-west Mau and Trans-Mara forests. Hall and Rodgers (1997) study on the effects of pole-cutting on forest in Tanzania was the first study of the impacts of this form of wood use in East Africa. Bamboo (Arundinaria alpina) (Wimbush, 1945; Kigomo, 1988; Were, 1988) and Juniperus procera are both extensively used for fuel and building materials in Afromontane areas of East Africa. As a relatively fire sensitive species which does not readily re-sprout, Juniperus procera use is an issue of possible concern, both to local people who value this resource, and from a conservation perspective. An MSc study (McGill University, Canada) started in early 1997 on comparing the biology and use of Juniperus procera and Olea europea subsp. africana by the Maasai in the Loliondo area, Tanzania. In the Tana River area, Kinnaird (1992) assessed the impact of harvesting Phoenix reclinata products, including stems for building poles. This was also identified as an important issue for further research in Uganda (Cunningham, 1994), where there is a large commercial trade in Phoenix reclinata stems for construction and fencing purposes in Kampala. Kakuru (1996) has included this as part of his current PhD study.

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7. Plants in domestic use

In urban areas, uniform, factory produced utensils and tools predominate. By contrast, wild plants continue to provide a wide range of items for home use in many rural communities in southern Africa ranging from drying racks for pots and pans, axe and hoe-handles, grain stamping mortars or general purpose rope. In Zimbabwe, for example, woodland trees were a source of 96% of domestic utensils, 98% of agricultural tools and 94% of rope and cord (Campbell et al., 1991). Just as wood-carving skills are best developed in woodland savanna, so basketry skills are most highly developed among agricultural communities in the large portion of southern Africa covered by sandy soils, where pottery clay is scarce and weaving fibre abundant from sedges and palms from high water-table sites. Although over 100 indigenous plant species are used as traditional dyes and fibres for basketry in southern Africa (Cunningham, 1987; Shaw, 1992), three plant genera (five species) are the major plant resource base of most basket production in the region. These are first, the long, strong leaf blades of Hyphaene palms (Arecaceae) as the main fibre for weaving baskets. Second, the bark and roots of the trees Berchemia discolor (Rhamnaceae) and two Euclea species (E. divinorum and E. natalensis (Ebenaceae) which are a favoured dye source due to their strong colour and colourfast nature. In Namibia, Botswana and western Zimbabwe, Hyphaene petersiana is used, occurring most commonly on alkaline, clay rich sands. By contrast Hyphaene coriacea palms are most common on leached, acid, high watertable sands along the eastern seaboard.

As industrially produced goods become easily available at lower cost and lifestyles change, so plant use for domestic use also changes. This is particularly evident as baskets give way to plastic and enamel bowls. In addition, baskets do not last long in normal household use, leaving little evidence of changing basket styles. For this reason it is fortunate that detailed studies and well documented, representative collections have been made of domestic use of wood (Hooper, 1981), basketry (Shaw, 1992) and material culture in general (Davidson, 1984; Shaw and van Warmelo, 1972, 1988). In a professional career spanning over 60 yr, ethnologist Margaret Shaw has made an outstanding contribution in this field, ranging from publications on Owambo knives (Shaw, 1938) to her detailed study documenting basketry techniques and documentation of a collection of over 2 500 specimens in the South African Museum, Cape Town (Shaw, 1992).

Although basket production for local use is in decline, it has been promoted as a rural development option for rural people in several drought susceptible or semi-arid areas of Africa, including Botswana, Namibia, South Africa and Zimbabwe. The largest volume of baskets produced for export from southern Africa are made in Botswana, Zimbabwe and South Africa using the same wild plant species or genera for fibre, from either of two Hyphaene palm species or from baobab bark. In East Africa, Hyphaene compressa is the main source of fibre for coil-built baskets, and sisal (the introduced, cultivated species Agave sisalana) a major source of woven sling-bags for export and local sales. Moyo (1995) and Kwaramba (1996) have recently completed studies on the value and impact of baobab bark collecting in Zimbabwe, where there has been a rapid increase in basket production and sales. One result has been an increase in frequency and intensity of harvesting, sometimes with negative consequences for the natural resource base of the basketry industry.

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8. Commercial trade in woodcarvings

Marshall and Jenkins (1994), in their review of hardwood trade in Kenya, suggested that the trade in woodcarving merited further study to determine the number of active carvers, the quantities, sources and species of wood used and the impact of woodcarving on tree populations. A 2 year study funded through the National Museums of Kenya by the WWF/UNESCO/Kew "People and Plants" Initiative is nearing completion (Obunga, 1995; Obunga and Sigu, 1996). This follows earlier studies in Kenya on the woodcarving industry (Elkan, 1958) and a short descriptive article by Troughear (1987). One of the results will be a clear picture of the massive extent of this trade, its national economic value and the status of the four most important species (Dalbergia melanoxylon, Brachylaena huillensis, Combretum schumannii and Olea africana) in selected sites and of appropriate alternative species such as Azadirachta indica (neem).

Four of the about 900 woodcarvers who are affilated to the Gikomba cooperative society in Nairobi, Kenya.

In southern Africa, the quantity and species used for carved items sold by a craftwork project in the Ingwavuma district, KwaZulu/Natal were documented by Cunningham (1987). More recently, Tooley (1996) studied the woodcarving industry of the Thukela valley in KwaZulu/ Natal, South Africa. Much smaller volumes of carved timber are sold in southern Africa compared to East Africa, but the volume of trade is growing. In Zimbabwe, for example, a study of woodcarving by Matose et al. (in press) along the Victoria Falls-Bulawayo road, which estimated that 657 m3/yr was being cut, primarily Afzelia quanzensis, Pterocarpus angolensis and Kirkia acuminata. Although this only represented 13% of the 5,000 m3/yr of timber cut in the same area by concessionaires (Forestry Commission, 1995) the number of people in the woodcarving industry, and quantity of wood cut is considered likely to rise dramatically.

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9. Institutional roles and "people management" vs. "resource management"

Understanding of ecological factors in natural resources management is crucial, but it is not enough. A large component of "resource management" really is "people management", and the social, economic or political factors that lead to resource conservation or to over-exploitation are as important and complex as the ecological component. For good science to become good management requires an understanding of social issues and acceptance of management plans or regulations. Many studies have been done in Zimbabwe on the social and political factors that are necessary for conservation and resource management (e.g., Murombedzi, 1990a,b, 1991; Hasler, 1991; McGregor, 1991; Fortmann, 1991/92; 1992a,b,c; Fortmann et al., 1992; Clarke, 1995; Matose and Wily, 1996) and to a lesser extent in East Africa (Wily, 1993; Wily and Haule, 1995). Literature on the CAMPFIRE programme in Zimbabwe in summarised by Dix (1995/96). There is a great need, however, for careful analysis of this issue that develops common principles and avoids mistakes arising from transplanting what succeeds in one location to places where they will fail for social, cultural or ecological reasons.

10. Back to the future: the neglected harvest

Cross-section of Landolphia kirkii with latex channels visible in the cortex.

In the nineteenth and early twentieth century, colonial botanists and agriculturalists screened the African flora for agricultural or industrial potential to Europe. Customary knowledge of African people was one of the keys used to identify potentially important plants. Likely candidates with commercial potential were then sent to the Imperial Institute in London for testing.

This included Hibiscus cannabinus fibre sent from Zimbabwe, roots of Mondia whitei, a traditional Zulu medicine proposed for flavouring soft drinks, wax from fruits of the coastal Fynbos shrub Myrica cordifolia for polish, gum from Acacia karoo for gum arabic and latex from Landolphia kirkii, Ficus vogelii, Tabernaemontana elegans, Maytenus acuminata and Voacanga thuoarsii as possible sources of rubber (Sim, 1920). Euphorbia latex was also exported from Namaqualand and the eastern Cape during this period, for the manufacture of American chewing gum (Brown and Brown, 1935). Marketing of rooibos tea from the Fynbos endemic, Aspalathus linearis was started in 1902 by B Ginsberg (Pty) Ltd. Other exports followed. Nearly 400 tons of bitter aloe (Aloe ferox) resin were exported annually to Europe between 1929-1932, while in 1930, 71 tons of buchu (Agathosma betulina) were exported to Japan for medicinal purposes (Brown and Brown, 1935). Although there are failures on the path from wild harvested resources to the shop counter, a successful and lucrative trade developed for some species - as it will do for new species in the future.

In the 1870's, the Africa oil-palm (Elaeis guineensis) was first introduced to Malaysia from West Africa, the banana was a curiosity in the USA and it would be almost a century before anyone heard of the kiwi fruit. Today, the oil-palm is a cornerstone of the Malaysian economy, bananas are a major export of many tropical countries and the kiwi fruit, indigenous to China, has become synonymous with New Zealand. African oil palms (Elaies guineensis) from the wild in West Africa can take up to 30 yr to reach fruiting stage. Selected domesticated varieties in Malaysia now only need 2-3 yr (Comte, 1991). Selected southern African wild plants could follow the same path. The only recent systematic survey of wild plant resources was done in Botswana, identifying several wild plant resources with commercial potential (Taylor, 1982; Taylor and Moss, 1982). Within the African region, there are several categories of plants that could generate income and employment, either from wild harvest or developed as new crops:

• edible wild plants and oilseeds.
• aromatic plants as potential sources of essential oils, particularly from Asteraceae (e.g., Pteronia, Eriocephalus), and Rutaceae (Agathosma, Coleonema, Diosma)
• genetic material of wild relatives of crop, forage and pasture species such as melons (Curcurbitaceae, Desert and semi-arid savanna of Namibia and Botswana), forage and pasture grasses;
• horticultural plants, such as several spectacular Crinum species (Amaryllidaceae) characterizing floodplains of northern Namibia and Zimbabwe in the Savanna biome, Gerbera and Gazania species (Asteraceae) in Grassland and Karoo biomes, and the spectacular bulbous species of the Fynbos biome in the Iridaceae (Freesia (11 species), Gladiolus (69 of c.150 species in the Cape flora), Babiana (36 species in the Cape flora) and Hyacinthaceae (Lachenalia (80 species, mainly in the Cape flora, but some in Namibia), Ornithogalum (31 species in the Cape flora, others widespread in southern Africa);
• herbal teas, primarily from the Fynbos biome, mainly Papilionaceae: (Aspalathus (255 species, only one species (A. linearis) the current export focus) and Cyclopia (20 species with eight species identified as tea sources by Kies (1951);In addition, new technologies such as automated screening programmes, new cancer cell lines and HIV screens for new natural products development for the pharmaceutical industry, boosting work on medicinal plants such as Hypoxis rooperi.

Apart from a few exceptions however, more interest has been shown in developing these resources from outside the region than within it. Research is being carried out on edible fruit bearing trees Sclerocarya birrea, Strychnos spinosa and Schinziophyton rautanenii is Israel (Cherfas, 1989) and plantations of Euphorbia tirucalli have also been developed on Okinawa island by a Japanese plastics company (Calvin 1979). The major commercial production of bulbs from the southern Africa flora is in Holland. Cultivation of the Kalahari marama bean Tylosema esculenta, internationally recognized as an important crop plant (NAS 1979) has been implemented in Texas (Bousquet 1982). The value of lost opportunities in generating income and employment within southern Africa can only be guessed. What we do know is that Freesia flowers sold at two Dutch auctions alone were valued at R300 million annually and that more cultivars of Lachenalia, Kniphofia, Agapanthus and Gladiolus are available to gardeners in the United Kingdom than to gardeners in southern Africa (Ivey, 1993).

Encouraging exceptions to the lack of recent applied work on genetic enhancement or cultivation of indigenous plant resources with potential are the selection of marula (Sclerocarya birrea) cultivars (von Teichmann 1983; van Wyk, 1987; Goosen 1985), Anisophyllea pomifera, Uapaca kirkiana and Schinzophyton rautanenii in Zambia (Leakey and Newton, 1994; Ngulube, Hall and Maghembe, 1996) and great interest in the Shea butter tree (Vitellaria paradoxa) project in semi-arid East Africa. Extensive work has been done on this species elsewhere (e.g., Booth and Wickens, 1988; Menninger, 1977; FAO, 1988, Wickens, 1995), including some nutritional analysis (FAO, 1988). In South Africa, developments have been the cultivation of plants for essential oils (Piprek et al., 1982; Graven et al., 1988), rooibos tea (Aspalathus linearis) (Morton, 1982), the cut-flower industry in the Fynbos biome (Davis, 1984) and ferns for florist materials (Milton, 1991). Far more applied research and resource development could be done. Although tree crops are slow growing, several species with commercial potential for fruits, such as Sclerocarya birrea and Schinziophyton rautanenii grow easily from truncheons. This greatly speeds up the selection and commercial cultivation process. Wild stocks can also supplement commercial production until plantations can be harvested. In South Africa, production and marketing of marula liqueurs and fruit juice developed from wild collected fruits bought from rural communities before commercial production from elite cultivars. By 1987, 2,000 tons of fruit were being processed into liqueur, 500 tons into fruit juice and 40,000 bottles of marula jelly were being made (van Wyk, 1987). The selection of marula (Sclerocarya birrea) fruits with commercially desirable qualities was done by Prof L.C. Holtzhausen from wild genotypes over a relatively short period of time and registered varieties are now being mass produced and planted out in the northern Transvaal savanna. Graven et al. (1988) have similarly worked on the selection of Artemisia afra genotypes that have high yields of selected essential oils.

Wild plant products can also be valuable through import substitution. The oil and protein rich marula kernel is a source of oil that is ten times more stable than olive or sunflower oils (Burger et al., 1987). This makes it a highly suitable oil as a replacement for high oleic oil from safflowers (Carthamnus tinctorius) imported for use in baby food formulas. Marula oil is also suitable as a substitute for oil used to coat dried fruit, as 250 tonnes of oil are used annually for this purpose in South Africa (du Plessis, 1988). Gum arabic production in Kenya and Zimbabwe, for example, saves importing gum arabic from Sudan.

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11. The hidden economy

Far less obvious than sale of rooibos tea or marula liqueur is the "informal sector" trade in plant products. The economic value of this trade is also far more difficult to assess, yet is important at a household level and frequently, on a regional scale. Trade or barter in plant products occurs in rural areas throughout Africa, where wild plant resources provide a wide range of products that are bartered or sold: dietary supplements, thatch, fuel, craftwork materials, honey, edible insects such as mopane "worms" (caterpillars of the moth Gonimbrasia belina), traditional dyes, perfumes and medicines. Trade in miombo woodland products is documented by Brigham, Chihongo and Chidumayo (1996). Literature on mopane caterpillars is reviewed by Hobane (1994), who has studied the mopane caterpillar trade in Zimbabwe (Hobane 1994b, 1995). Munthali and Mughogho (1992) surveying resource use by local people around Kasungu National Park, Malawi, found that honey and edible caterpillar collecting were the most important resource access issues in this miombo woodland area. Silow (1976) working Zambia and Quin (1959) and Cunningham (1985) in South Africa all document the use and nutritional values of edible insects.

In addition to barter or trade of plant resources at a homestead level, sales of crafts, medicinal plants and bush-foods commonly take place at roadside stalls, cattle auctions, bus-stops and taxi ranks. Naturalised species are also a source of lucrative trade. Cannabis (Cannabis sativa), originally from Asia, is an important (but illegal) cash crop of small-scale farmers in Transkei and KwaZulu. Prickly pears (Opuntia ficus-indica) introduced from South America and particularly abundant in the eastern Cape and Karoo are traded informally and urban fresh produce markets (Brutsch and Zimmerman, 1993). Invasive Australian Acacia species (A. cyclops and A. saligna) form the basis of a charcoal industry valued at R3.52 million/yr (US$1 million) and fuelwood sales of R24.7 million/yr (US$8 million) (Azorin, 1992). Harvesting any of these plant products is usually labour intensive with low financial returns. Nevertheless it provides a source of income to probably hundreds of thousands of rural families in southern Africa.

Trade in crafts and palm wine are good examples of this. In 1984, 14 years after commercial basket production first started in Botswana, about half of the female population of Etsha (ca. 1,500 women) and 400 women in Gomare/Tubu villages in Ngamiland were making baskets commercially (Terry, 1984, 1987). In KwaZulu/Natal, South Africa, for example, culms of the saltmarsh plant Juncus kraussii are the most favoured material for sleeping mats. From 1970-1990 for example, an average of 2,823 women harvested mat rush (Juncus kraussii) from coastal saltmarsh at St Lucia estuary, Natal. In 1990 alone, 3,831 women removed an estimated 50.9 tons of selected matrush culms from a 20 ha area which was then resold throughout the province or made into crafts for export. Trade networks are as complex as they are unobtrusive.

A study of the palm wine trade in Hyphaene coriacea palm savanna in South Africa provides a detailed example of an informal trade network linking palm sap tappers with the sale, transport and resale away from the palm savanna. Although volume of palm wine transported was large, with nearly 980,000 litres of undiluted palm wine sold in a 12 month period, individual incomes were low (R30-R70/month (1982)) and required labour intensive work. A single tapper constantly maintained a tapping rotation within a set area, tapping 712 palms (902 stems) in a 12 month period. Sales varied markedly between the four palm wine sale points in the study area (Cunningham, 1990a). They also fluctuated in response to factors ranging from competition with marula (Sclerocarya birrea) beer brewing season through to vehicle breakdowns. Despite these difficulties, the palm wine trade provided a means of self-employment to 460-480 people in the study area and together with cattle-grazing, basket weaving and gathering of bush foods, an important multiple-use of palm savanna.

The subsistence use of forest products in Kenya has been assessed by Emerton (1996). In southern Africa, the most detailed valuation studies have been carried out in woodlands in Zimbabwe (Campbell 1994; Campbell and Bradley, 1994; Campbell et al., 1995; in press; Hot Springs Group, 1995; Lynam et al., 1994). Shackleton (1996) has published one of the few woodland valuation studies in South Africa. In these cases, the value of trees fell into three main categories. First, the direct values to households for fuel, farm and household materials. Second, their value in terms of production as crop inputs such as leaf litter, animal feed and cash income. Thirdly, trees provided a range of services, ecologically, socially and for shade. Although fuelwood and construction timber made up a high proportion of the total value in miombo woodland, however, the value of wild fruits, browse and litter inputs for fields were as valuable (Nyathi and Campbell, 1993). These values decline with reduction in tree cover or with species specific overexploitation.

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12. Future directions for an African ethnobotany network?

There is no doubt of the importance of ethnobtanical studies to both conservation and development in Africa: plants provide a "green social security" in the form of low-cost housing, fuel, subsistence income, food supplements and herbal medicines in a continent where social security is rarely provided. Loss of this green safety net through agricultural clearing, intensive grazing or overexploitation has serious consequences for both rural and urban areas as the rural poor become rural refugees in urban shanty towns at great social and economic cost. What is needed is for a greater commitment to more rigorous research in this field: particularly quantitative studies and research to test hypotheses on people-plant interactions. If this is done, it will not only contribute to development of this field of study, but demonstrate that ethnobotany is not the popular "soft option" of merely listing species and uses but can make a substantial contribution to our understanding of people-environment interactions, taxonomy, chemistry and human health issues in Africa

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