BackgroundAngola suffered a long-lasting military conflict. Therefore, traditional knowledge of plant usage is still an important part of cultural heritage, especially concerning the still very poor health care system in the country. Our study documents for the first time traditional knowledge of plant use of local Bakongo communities in the northern province of Uíge on a large scale with a focus on medicinal plants and puts data in context to different parameters of age, gender and distance to the provincial capital.MethodsField work was carried out during nine field trips in 13 municipalities between October 2013 and October 2016. In 62 groups, 162 informants were interviewed. Herbarium specimens were taken for later identification. Database was analysed using Relative Frequency of Citations, Cultural Importance Index, and Informant Consensus Factor. Furthermore, significances of influence of age, gender and distance were calculated.ResultsOur study presents 2390 use-reports, listing 358 species in 96 plant families, while just three out of 358 mentioned species are endemic to Angola about one-fifth are neophytes. The larger the distance, the higher the number of use citations of medical plants. Although women represent just a fifth of all citations (22%), their contribution to medicinal plants was proportionally even higher (83%) than those of men (74%). Fifty percent of all plants mentioned in the study were just listed by men, 12% just by women. We made some new discoveries, for example. Gardenia ternifolia seems to be promising for treatment of measles, and Annona stenophylla subsp. cuneata has never been ethnobotanically nor phytochemically investigated.ConclusionsWhile the study area is large, no significant influence of the distance in regard to species composition in traditional healer’s concepts of the respective village was pointed out. Although several plants were just mentioned by women or men, respectively, no significant restriction to gender-specific illnesses in medical plant use could be found. Merely concerning the age of informants, a slight shift could be detected.Graphical abstractVisual representation of the ethnobotanical study in Uíge, northern Angola.Electronic supplementary materialThe online version of this article (10.1186/s13002-018-0238-3) contains supplementary material, which is available to authorized users.

The wide use of natural fibers has a long-standing history in Africa. In northern Angola, three native fiber plant species, namely Urena lobata, Triumfetta cordifolia, and Dombeya burgessiae, were investigated with regard to their potential usage in modern applications, such as green composites. Bast fibers of the three species were analyzed morphologically, chemically, and mechanically to determine properties such as fiber density, cellulose content, Young's modulus, tensile strength, and breaking strain. In comparison to other natural fibers, all three species were characterized by high Young's moduli up to 60 GPa and tensile strengths up to 950 MPa, yet retting is crucial to unfold the maximum strength of the fibers. Extending the retting time revealed higher values but probably negatively influences economic efficiency. The results demonstrated that the analyzed plants deliver strong and resistant fibers; based on their biomechanical performance, they are alternatives to commercially used natural fibers, such as jute (Corchorus spp.). However, as with other natural fibers, there was high variation in the mechanical properties in the studied species.

From 2013-2017, we accompanied and interviewed local people harvesting edible insects in the Northern Angolan province of Uíge. Insect and host plant samples were collected for species identification and nutritive analyses. Additionally, live caterpillars were taken to feed and keep until pupation and eclosion of the imago, necessary for morphological species identification. Altogether, 18 insect species eaten by humans were recorded. Twenty four edible insect species were formerly known from the country, four of which are confirmed in this study and 14 species additionally recorded. Sciatta inconcisa Walker, 1869 (Erebidae) and Gastroplakaeis rubroanalis Wichgraf, 1913 (Lasiocampidae) are reported for the very first time as human dietary foods. All 18 species are illustrated and DNA-Barcodes are provided to enable reidentification of species. Though much effort has been undertaken for the identification of the 18 species, only 14 species have been identified at species level and another four only at family level. The scientific names are listed along with the vernacular names. A nutritional analysis is provided for nine species most of which are consumed in the villages, but some are also traded, for which a market study has been conducted. Information is also given on traditional collection and preparation as well as cultural aspects of edible insects in Northern Angola.

Background and aims – Located in the transition zone of Guineo-Congolian and Zambezian phytochoria, the Angolan provinces of Uíge and Cuanza Norte are of particular interest for floristic studies and high biodiversity is expected. Nevertheless, explorations of the vegetation are relatively rare. Our study aims to supplement a recent checklist of vascular plants of Angola. Methods – Data were collected during 17 field trips between 2013 and 2018, during which herbarium specimens were prepared for later identification of plant species. The results were compared with the current checklist as well as with other floristic works, herbarium collections and online databases relevant for the region.Key results – We document 20 new records of indigenous vascular plant species for the flora of Angola (19 species and one subspecies), including four new generic records. Furthermore, nine alien species are added to the checklist of the flora of Angola.Conclusion – Our results confirm that the flora of northern Angola is composed by elements of various adjacent areas. However, not all species present are known yet. Further botanical investigation is needed to complete our floristic knowledge of the region.

Background Worldwide, different traditions of symbolic statements in graveyards can be found. However, studies on sub-Saharan Africa are rare. For BaKongo cemeteries, it is only known that they traditionally do not exhibit plants for decoration purposes. Our study wanted to inspect the influence of Portuguese culture due to the long shared colonial past. Methods During 2015 and 2019, plant use in 87 graveyards in 13 municipalities of the province Uíge was documented. Five expert interviews with the village eldest in five municipalities completed the data collection. Results While 24% of the graveyards didn´t have any planting, 27 plant species were found in the remaining ones, including a high percentage of alien species (59%), mainly from the Americas. The most abundant plant species are Euphorbia tirucalli (23%) and Agave sisalana (22%). With increasing distance from the city Uíge (especially towards the Democratic Republic of the Congo), the utilization of living plants in cemeteries is decreasing except along the road. In most of the cases, just one plant species per gravesite was found. Conclusions This unexpected high number of plants might be interpreted as a strong evidence of outside influence. Cultural symbols of the BaKongo cosmology and Christianism appear to coexist or coalesce. Furthermore, plants are used as a marker for graveyards. Modern influences like the use of concrete in proximity to urban areas indicate a certain wealth.