DNA barcoding augments conventional methods for identification of medicinal plant species traded at Tanzanian markets.

ETHNOPHARMALOGICAL RELEVANCE: In Africa, traditional medicine is important for local healthcare and plants used for these purposes are commonly traded. Identifying medicinal plants sold on markets is challenging, as leaves, barks and roots are often fragmented or powdered. Vernacular names are often homonymic, and identification of material lacking sufficient morphological characters is time-consuming, season-dependent and might lead to incorrect assessments of commercialised species diversity. AIM OF THE STUDY: In this study, we identified cases of vernacular heterogeneity of medicinal plants using a tiered approach of literature research, morphology and DNA barcoding. MATERIAL AND METHODS: A total of 870 single ingredient medicinal plant samples corresponding to 452 local names were purchased from herbal markets in Dar-es-Salaam and Tanga, Tanzania, and identified using conventional methods as well as DNA barcoding using rbcL, matK and nrITS. RESULTS: Using conventional methods, we could identify 70% of samples to at least family level, while 62% yielded a DNA barcode for at least one of the three markers. Combining conventional methods and DNA barcoding, 76% of the samples could be identified to species level, revealing a diversity of at least 175 species in 65 plant families. Analysis of the market samples revealed 80 cases of multilingualism and over- and under-differentiation. Afzelia quanzensis Welw., Zanthoxylum spp., Allophylus spp. and Albizia anthelmintica Brongn. were the most evident cases of multilingualism and over-differentiation, as they were traded under 8-12 vernacular names in up to five local languages. The most obvious case of under-differentiation was mwingajini (Swahili), which matched to eight scientific species in five different plant families. CONCLUSIONS: Use of a tiered approach increases the identification success of medicinal plants sold in local market and corroborates findings that DNA barcoding can elucidate the identity of material that is unidentifiable based on morphology and literature as well as verify or disqualify these identifications. Results of this study can be used as a basis for quantitative market surveys of fragmented herbal medicine and to investigate conservation issues associated with this trade.

Trade in Zambian Edible Orchids-DNA Barcoding Reveals the Use of Unexpected Orchid Taxa for Chikanda.

In Zambia, wild edible terrestrial orchids are used to produce a local delicacy called chikanda, which has become increasingly popular throughout the country. Commercialization puts orchid populations in Zambia and neighbouring countries at risk of overharvesting. Hitherto, no study has documented which orchid species are traded on local markets, as orchid tubers are difficult to identify morphologically. In this study, the core land-plant DNA barcoding markers rbcL and matK were used in combination with nrITS to determine which species were sold in Zambian markets. Eighty-two interviews were conducted to determine harvesting areas, as well as possible sustainability concerns. By using nrITS DNA barcoding, a total of 16 orchid species in six different genera could be identified. Both rbcL and matK proved suitable to identify the tubers up to the genus or family level. Disa robusta, Platycoryne crocea and Satyrium buchananii were identified most frequently and three previously undocumented species were encountered on the market. Few orchid species are currently listed on the global International Union for the Conservation of Nature (IUCN) Red List. Local orchid populations and endemic species could be at risk of overharvesting due to the intensive and indiscriminate harvesting of chikanda orchids, and we therefore encourage increased conservation assessment of terrestrial African orchids.

Quantitative market survey of non-woody plants sold at Kariakoo Market in Dar es Salaam, Tanzania.

ETHNOPHARMACOLOGICAL RELEVANCE: In Tanzania, traditional medicine plays a significant role in health care and local economies based on the harvesting, trade and sale of medicinal plant products. The majority of this plant material is said to originate from wild sources, and both traditional healers and vendors are concerned about the increasing scarcity of certain species. AIM OF THE STUDY: A market survey of non-powdered, non-woody medicinal plants was conducted at Kariakoo Market in Dar es Salaam, the major hub for medicinal plant trade in Tanzania, to assess sustainability of traded herbal medicine. MATERIALS AND METHODS: For this study, fresh and dried herbs, seeds and fruits were collected and interviews were conducted to obtain information on vernacular names, preparation methods, monthly sales, uses and prices. Bundles of herbal medicine offered for sale were weighed and counted to calculate the value and volumes of daily stock at the market. RESULTS: A total of 71 medicinal plant products belonging to 62-67 different species from at least 41 different plant families were identified. We identified 45 plant products to species level, 20 products to genus level and four to family level. Plant species most encountered at the market were Suregada zanzibariensis, Myrothamnus flabellifolia and Sclerocarya birrea. The major use categories reported by the vendors were ritual purposes, digestive disorders and women's health. Annual sales are estimated to be in excess of 30 t and close to 200,000 USD, and trade in herbal medicine at Kariakoo Market provides subsistence income to many local vendors. CONCLUSIONS: A large diversity of wild-harvested plant species is traded as medicinal products in Tanzania, including species listed on CITES Appendices. Identifying and monitoring temporal changes in availability per season and from year to year will reveal which species are most affected by this trade, and help relevant authorities in Tanzania to find alternative sources of income for dependent stakeholders and initiate targeted efforts to protect threatened plant species.

Vernacular dominance in folk taxonomy: a case study of ethnospecies in medicinal plant trade in Tanzania.

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.

Molecular species delimitation in the Racomitrium canescens complex (Grimmiaceae) and implications for DNA barcoding of species complexes in mosses.

In bryophytes a morphological species concept is still most commonly employed, but delimitation of closely related species based on morphological characters is often difficult. Here we test morphological species circumscriptions in a species complex of the moss genus Racomitrium, the R. canescens complex, based on variable DNA sequence markers from the plastid (rps4-trnT-trnL region) and nuclear (nrITS) genomes. The extensive morphological variability within the complex has led to different opinions about the number of species and intraspecific taxa to be distinguished. Molecular phylogenetic reconstructions allowed to clearly distinguish all eight currently recognised species of the complex plus a ninth species that was inferred to belong to the complex in earlier molecular analyses. The taxonomic significance of intraspecific sequence variation is discussed. The present molecular data do not support the division of the R. canescens complex into two groups of species (subsections or sections). Most morphological characters, albeit being in part difficult to apply, are reliable for species identification in the R. canescens complex. However, misidentification of collections that were morphologically intermediate between species questioned the suitability of leaf shape as diagnostic character. Four partitions of the molecular markers (rps4-trnT, trnT-trnL, ITS1, ITS2) that could potentially be used for molecular species identification (DNA barcoding) performed almost equally well concerning amplification and sequencing success. Of these, ITS1 provided the highest species discrimination capacity and should be considered as a DNA barcoding marker for mosses, especially in complexes of closely related species. Molecular species identification should be complemented by redefining morphological characters, to develop a set of easy-to-use molecular and non-molecular identification tools for improving biodiversity assessments and ecological research including mosses.