Otieno et al. Journal of Ethnobiology and Ethnomedicine 2015, 11:10 http://www.ethnobiomed.com/content/11/1/10 JOURNAL OF ETHNOBIOLOGY AND ETHNOMEDICINE RESEARCH Open Access Vernacular dominance in folk taxonomy: a case study of ethnospecies in medicinal plant trade in Tanzania Joseph Otieno1, Siri Abihudi1, Sarina Veldman2, Michael Nahashon2, Tinde van Andel3 and Hugo J de Boer2,3,4* Abstract Background: Medicinal plants are traded as products with vernacular names, but these folk taxonomies do not always correspond one-to-one with scientific plant names. These local species entities can be defined as ethnospecies and can match, under-differentiate or over-differentiate as compared to scientific species. Identification of plant species in trade is further complicated by the processed state of the product, substitution and adulteration. In countries like Tanzania, an additional dimension to mapping folk taxonomies on scientific names is added by the multitude of ethnicities and languages of the plant collectors, traders and consumers. This study aims to elucidate the relations between the most common vernacular names and the ethnicity of the individual traders among the medicinal plant markets in Dar es Salaam and Tanga regions in Tanzania, with the aim of understanding the dynamics of vernacular names in plant trade. Methods: A total of 90 respondents were interviewed in local markets using semi-structured interviews. The ethnicity of each respondent was recorded, as well as the language of each ethnospecies mentioned during the interviews. Voucher collections and reference literature were used to match ethnospecies across languages. Results: At each market, the language of the majority of the vendors dominates the names for medicinal products. The dominant vendors often represent the major ethnic groups of that region. Independent of their ethnicity, vendors offer their products in the dominant language of the specific region without apparently leading to any confusion or species mismatching. Conclusions: Middlemen, traders and vendors adapt their folk classifications to those of the ethnic groups of the region where they conduct their trade, and to the ethnicity of their main customers. The names in the language of the traders are not forgotten, but relegated in favor of the more salient names of the dominant tribe. Keywords: Vernacular names, Medicinal plants, Wildlife trade, Tanzania, Sub-Saharan Africa, Traditional medicine, Folk taxonomy Background a thriving trade in both rural and urban areas [4-8]. An In Africa, traditional healers and remedies made from estimated 5400 plant species are used in traditional plants play an important role in healthcare for millions medicine in Africa [9]. Estimates of the number of spe- of people [1,2]. The often-quoted World Health Organ- cies used in Tanzania vary from 405 [10] to 1100 [11], ization estimate that up to 80% of population depends on although many authors agree that too little is currently traditional medicine for their primary healthcare [3], is known [6,12]. particularly apt for Tanzania where traditional medicine is Studying medicinal plants traded in markets has been used to quantify the commercialization and utilization of * Correspondence: [email protected] natural products, as these mirror a region’s culture, and 2Department of Organismal Biology, Evolutionary Biology Centre, Uppsala can give a rapid insight into traditions, salient health University, Norbyvägen 18D, SE-75236 Uppsala, Sweden 3Naturalis Biodiversity Center, Darwinweg 4, Postbus 9517, 2300 RA Leiden, problems and the importance of herbal medicine in local The Netherlands health care [13-21]. In addition, surveys of traded medicinal Full list of author information is available at the end of the article © 2015 Otieno et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Otieno et al. Journal of Ethnobiology and Ethnomedicine 2015, 11:10 Page 2 of 7 http://www.ethnobiomed.com/content/11/1/10 products can reveal the diversity and prevalence of these ethnospecies and scientific names of products in trade items [14,15] and can help to estimate the total traded are substitution and adulteration. Adulteration is the species richness [16,17,20,21]. Nevertheless, some parts intentional replacement of the intended species for of the local pharmacopeia may be overlooked, and it another, while substitution is more broadly defined and has been asserted that species entering commercial can include slow general substitution of one species for trade represent a ‘short-list’ of a far greater diversity of another due to overharvesting and depletion of the species used for subsistence in rural areas [13]. original species [18,30]. Substitution and adulteration are The rich floral biodiversity of Tanzania with over not only challenging for scholars of folk taxonomies, but 11,000 species [22], the estimated number of 5400 can also be confusing for traders [19] and customers [30]. species used in traditional medicine in Africa [9], and In Tanzania, as elsewhere in Africa, an additional dimen- species diversity in markets in South Africa [14], Benin sion to mapping folk taxonomies on scientific names is [20], Gabon [23], Ghana [21] and Morocco [18] suggest added by the multitude of ethnicities and languages of the that between 200–800 species could be traded in plant collectors, traders and consumers [34,35]. Tanzania. However, published structured quantitative This study aims to elucidate the origins of the ver- research on medicinal plant trade in the markets of nacular names used for the most common ethnospecies Tanzania is so far lacking, and less than 200 plant in the Tanzanian medicinal plant trade. Our null hypoth- species have been documented from trade [12,24-27]. esis was that traders use the vernacular names in their The two main cities trading wild-crafted medicinal own language for the ethnospecies they trade, while our plant products in Tanzania are Dar es Salaam with alternative hypothesis was that traders adjust the names approximately 70 vendors, and Tanga with ca. 50 vendors to those of the dominant group in the area in which they [24,25,28], but the actual numbers are probably signifi- trade. The following research questions are posed: 1) cantly higher. Commercial trade is said to be one of the What are the ethnicities of medicinal plant traders in largest threats to wild medicinal plant populations in Dar es Salaam and Tanga?; 2) What names do the traders Tanzania [24], and vendors in both markets have reported use for the products in their stalls?; 3) What are the most the coastal districts, as well as the Uluguru and Usambara likely scientific names for each of the ethnospecies?; 4) mountains, as the main sources of plant material [24]. Which vernacular name(s) are dominant per ethnospe- The main sources of wild-crafted medicinals coincide with cies?; and 5) What language dominates the medicinal the locations of some of the most threatened biodiversity plant trade and why? hotspots in Africa: the Coastal Forest of Eastern Africa and Eastern Afro-montane hotspots [29]. Methods If Tanzania is to provide a sustainable supply of herbal Study area medicine in the future, it needs to know which species are The study was carried out in Dar es Salaam and Tanga in danger of being overexploited. Knowing the medicinal regions from August 2013 to mid-April 2014. Dar es plant species in trade is a prerequisite for developing a Salaam city and Tanga town are the main hubs of the system of controlled sustainable exploitation. Priority medicinal plant trade in Tanzania [7,25,28]. Plant mate- species for conservation would be those that are wild- rials are supplied to here from the surrounding regions harvested in large quantities from vulnerable habitats of Arusha, Iringa, Lindi, Manyara, Morogoro, and Pwani. and reported to be increasingly difficult to obtain. Iden- These regions include two biodiversity hotspots that are tification of medicinal plants in trade is complicated, as recognized internationally for their high species diversity most material is traded in dried, shredded or powdered and endemicity—the Coastal Forests of East Africa and form [7,25,30]. the Eastern Afromontane Forests [29], which are import- Medicinal plants are traded as products with local ant sources of commercially-traded medicinal plants [7]. names in folk taxonomies [31]. These local species entities These coastal trade cities are melting pots of ethnicity, can be defined as ethnospecies and can match, under- culture and religion [7,36]. differentiate or over-differentiate as compared to scientific species. Under-differentiation in ethnospecies is the case Market survey when names are being applied to entire genera or unre- The survey focused on the main areas of medicinal plant lated species [13,31], while over-differentiating happens trade of Dar es Salaam city and Tanga town, these beyond the scientific species level to distinguish intraspe- included Kariakoo market in Dar es Salaam and various cific morphological or pharmacological characters, such as streets in Tanga town. In these areas traders