Composition of plants used in traditional cosmetics in Madda Walabu district

Despite the present study describing and documenting plants used as traditional cosmetics, these plants can be used for both cosmetic and medicinal purposes, and there can be some overlaps between these two categories in many cultures [34,35,36]. However, there are some key distinctions between the two: cosmetic applications are mainly used to enhance physical appearance or hygiene and may have some minor therapeutic effects, but are not intended primarily for treating medical conditions. Examples: moisturizers, hair conditioners, soaps, and perfumes [37]. Thus, the study mainly focused on the cosmetic role of the plants even though these plants can have medicinal applications in addition. The primary purpose of the plant applications was determined based on the information provided by the informants. Thus, based on the informants’ response, if the plant was primarily used to enhance physical appearance or hygiene, it was classified as a cosmetic application.

In various parts of the world including Ethiopia, many plant species are commonly used locally for the preparations of traditional cosmetics but have not been scientifically investigated for wider use [38]. This implies a need to collect and compile indigenous knowledge of plant-based traditional cosmetics among ethnic groups, specifically, the Oromo (largest ethnic group in Ethiopia) women of Bale lowland in this study. Accordingly, a total of 48 plant species used as traditional cosmetics were recorded of which Fabaceae, Bigonaceae, and Burseraceae were the most frequent families. The study thus revealed that there is a great diversity of plants for cosmetic use, which could be useful documentation, contributing to preserving the knowledge about the traditional cosmetic use of plants in this region. Consequently, the ethnobotanical study of these species reveals that the Oromo women in the Madda Walabu district possess a deep knowledge of local plants and their cosmetic applications. The traditional cosmetics they use reflect their cultural heritage and their connection to the natural environment. The study contributes to the documentation of ethnobotanical knowledge and provides insights into the potential for developing sustainable cosmetic products based on traditional practices.

The study documented a relatively higher number of species specifically used as traditional cosmetics compared to other similar studies (Table 9). This high number of species could be attributed to the varied agroecology and climatic conditions of our study area that supported a variety of plant species. A comparison of the species number discovered in different countries is presented below.

Table 9 Number of plant species used as a traditional cosmetic reported in different countries

Moreover, the top rank of Fabaceae which aligns with other studies [39], as a source of local cosmetics is not surprising for several reasons. First, Fabaceae is among the most species-rich families (3rd) in the flora area of the country [44, 45]. The same is true for the Burseraceae family since the vegetation of the study area is mainly Acacia commiphora woodlands [21]. The potential importance of the species as cosmetics in this family could therefore be a result of its representation in the flora of the area. Second, in neighboring districts with similar agroecology such as Dallo Manna [46] and Gura Damole districts [47], Fabaceae was found to contain many medicinal plants. However, the strange thing was that Lamiaceae which contains many cosmetic and medicinal plants that are of global importance [40, 48] was only represented by one species in the study area. The variation could be attributed to the differences in agroecology. Moreover, similar to other studies in Africa (tropical) that focused on traditional cosmetics [39,40,41], trees were the most commonly used plant life forms followed by shrubs and herbs. The high usage of such plant life forms in Madda Walabu is also likely associated with the tropical climate region which, in turn, helps the plants to be widely available and abundant in the study area.

Plant parts used and use category

Among a range of plant organs used in the study area, leaves are the parts that are most commonly used in traditional cosmetics which are in line with other studies [39, 40, 46, 47]. The preference for leaves as a major source of cosmetics could be asserted by the fact that they are not only easy to collect, store, and process during most of the year but also are the site of photosynthesis and sometimes the storage of bioactive ingredients responsible for the cosmetic properties of the plant helping beautification [49, 50]. The use of leaves as traditional cosmetics encourages conservation practices, unlike the extensive use of roots and barks which may cause the death of plants. However, reports from some other studies revealed that fruits were the most commonly used plant parts as cosmetics among women [2, 51]. The difference could be attributed to the variations in indigenous knowledge on plant-based cosmetics differing across different communities and ethnic groups globally.

A greater number of citations for cosmetic applications are exhibited in the fidelity level. In the current study, about 19 species were found to have FL values of greater than 88% suggesting that the state of knowledge of the informants is more or less common when it comes to the uses of such plants. However, species such as Terminalia brownii Fresen and Olea europaea L. subsp. cuspidata (Wall. ex G. Don for hair treatment and Terminalia laxiflora Engl. & Diels and Sesamothamnus rivae Engl. for skincare were the most frequently cited species among the Oromo women in the study area. Moreover, from the computation of relative frequency citations and cultural importance index, these same species were found to be the most frequently cited for use as traditional cosmetics and considered culturally more important among the Oromo women in the district. This could be due to their availability. For example, the genus Terminalia is the second largest genus of Combretaceae and is widely distributed in Eastern African countries such as Ethiopia [52]. Propagation can occur naturally through seeds or vegetative methods using wild plants, seedlings, tree stumps, or young plants [53]. Terminalia spp. provides economic, medical, spiritual, and social benefits in Ethiopia [54]. Similarly, Aloes are recognized as an important component of the dry-land ecosystems, primary colonizers of habitats that might enable later habitation by other less resilient plants. Areas that experience prolonged drought can benefit from the planting of Aloe [55]. Aloes are used in soap production, jute sack production, and hair washing [56]. The other reason could be related to their use, for skincare in which the skin is the largest organ exposed to external barrier, requires frequent care and treatment [40, 41, 57].

FL is a measure of the degree of effectiveness of the cosmetic plant for beautification. Thus, traditional cosmetic plants having high fidelity level values are speculated to be effective in their beautification potential and can be a good candidate for further detailed investigation. Although [17] reported the FL values of some of the aforementioned species for their medicinal aspect, no literature has documented their FL scores for cosmetic uses as the present study is the first of its kind in the area and also due to variations of the use of plants from area to area. From informant consensus factor analysis, high FIC values suggested that Oromo women in the community share knowledge about the most significant plant species of traditional cosmetics commonly used for beautification and low FIC values indicate less willingness to share knowledge of significant plant species of traditional cosmetics for beautification for women [58]. From the current study, although all the usage categories had higher values, face care has the highest FIC which further substantiates the heavy reliance of Oromo women of Madda Walabu district on plant-based traditional cosmetics.

Method of preparations and mode of application

As documented in other ethnobotanical studies in Bale [59], diverse methods of preparation were observed in the current study. Accordingly, maceration and decoction were the most frequently used preparation methods among the participants. This goes in line with other similar studies where decocting or concocting was mostly the more common way of preparation [50]. Furthermore, in the current study, most of the products of traditional cosmetics were administered topically which aligns with other several studies [57, 60]. This route of administration was demonstrated with eleven different cosmetic applications. Remarkably, this proves the certainty that plant species are intensely entrenched in the cosmetic globe with different kinds of cosmetic uses. Applications of natural-based cosmetics such as a paste, powder, or sap (topically) were also in alignment with the findings [34].

Plant-based traditional cosmetics and Oromo women's indigenous knowledge

The current study revealed significant variations in the number of plant species used as traditional cosmetics among Oromo women of different ages. Accordingly, older women mentioned and used more plant species as traditional cosmetics for beautification than younger ones. This aligns with the findings of [2] and [40] indicating that indigenous knowledge of plant-based traditional cosmetics is not equally distributed among the different age groups of women. Thus, the study revealed a well-established indigenous knowledge of plant-based cosmetics among the Oromo women but seems to decline with age which could be attributed to the low interest of the younger generation to inherit and use traditional cosmetics. The other finding of the current study is that Oromo women, who didn't attend formal education, are married, and housewives have more extensive knowledge of traditional cosmetics than students, educated and employed. This could be due to the inspiration of the younger women, educated and employed ones by intensive media campaigns and advertisements of synthetic cosmetics that might have resulted in decreasing interest in using natural cosmetics [2]. Thus, due to the declining trends of the use of plant-based traditional cosmetics in the younger generation, which was also supported by other studies [61], there is an urgent need to preserve the indigenous knowledge of the Oromo women of Madda Walabu district. We suggest that the younger generation should be trained and made aware of the importance, of sustainable utilization as well as the domestication of precious plant-based traditional cosmetics.

The type of occupation also plays a major role in the use of herbal cosmetics. We discovered that housewives use more cosmetic plants for their skin, face, hair, and teeth hygiene than women who work outside of the home. Housewives tend to have less income than working women, hence their higher interest in cheaper cosmetics. Similar studies in Egypt reported that herbal remedies are much more common among lower-income groups, such as students, housewives, and non-literate women [40]. On the contrary, the results of the study that took place in Finland revealed that women who had relatively high social status were the most interested in herbal remedies and cosmetics [62], suggesting that knowledge and use of herbal remedies may be context-specific. On the other hand, [63] reported that knowledge of medicinal plants was not related to age or gender in Brazil.

Besides the regular application of plant-based natural cosmetics, Oromo women knowledgeable about traditional cosmetics indicated that the different types of plant species are inspired mainly by their culture, and cosmetic products are mainly used in cultural practices such as traditional healing and skin-related issues. In contrast to other studies [58] that restrict outdoor activities including plant gathering from wild to men, our study revealed that nature-based cosmetic plant collection was carried out by women which aligns with [39].

Concerning traditional knowledge and cultural practices, the Oromo women made clear that their homemade cosmetics were prepared for the whole community and required different forms of preparation. Moreover, the knowledgeable respondents articulated that natural-based cosmetics are interdisciplinary practices that heal and promote the beauty of skin which is in line with [17].

Furthermore, the current study revealed that cosmetics play a significant role in cultural identity and expression. The use of specific plants for cosmetic purposes is often associated with cultural norms, values, and beliefs. For Oromo women, the use of traditional cosmetics is a way to express their cultural identity and connect with their heritage. For example, there was particular care for intimate hygiene which is typical of the Oromo women in the area that is called qayyachuu in Afan Oromo. It is the means of caring for private parts (vagina) through smoking and fumigation, particularly for married women which align with [17] but with a different name, woyeba chis meaning smoking bath in northern Ethiopia. The treatments are used to avoid bad smells, limit vaginal discharges, and can arouse the woman, making her ready for sexual activities. The wood materials for qayyachuu are mainly prepared from the mix of the barks and branches from plant species such as Commiphora baluensis Engl. C. habessinica (Berg) Engl. and C. myrrha (Nees) Engl.