Specialization in ethnomedicinal plant knowledge among herbalists in the forest region of Rivercess County , Liberia

The ethnomedicinal uses of plants reported by 22 herbalists in the Rivercess County of Liberia show a rich knowledge of medicinal plant usage for both common and less common health problems. We set out with the objectives of documenting the ethnomedicinal plant knowledge and assessing gender differences in the use of the plants by male and female herbalists. Through semi-structured interviews conducted with herbalists, a total of 112 species belonging to 52 families in 93 genera were recorded to be in use. Seven plant families were known to account for 43.9% of the total number of species utilized including Annonaceae, Apocynaceae, Costaceae, Rubiaceae, Euphorbiaceae, Fabaceae and Verbenaceae. Traditional herbalists comprising male (64%) and female (36%) possessed extensive knowledge of the use of these plants, with male and female herbalists showing specializations in several categories of health problems based on their knowledge of medicinal plants. Female herbalists possessed a slightly higher knowledge of ethnomedicinal plants than male herbalists. Many ailments were reported with a large number of the plants utilized for malaria, snakebites, ulcer, spiritual/witchcraft, infection and diarrhoea. New and unrecorded ethnomedicinal uses for several plants were documented, including Tetraberlinia tubmaniana J. Léonard, Delpydora gracilis A.Chev., Campylospermum subcordatum (Stapf) Farron, Cyathula prostrata Blume, Heisteria parvifolia Sm., Keetia rufivillosa (Robyns ex Hutch. & Dalz.) Bridson, Pavetta sonjae W.D.Hawth., Chrysophyllum pentagonocarpum Engl. & K.Krause, Placodiscus pseudostipularis Radlk, and the naturalized plant, Caladium bicolor (Aiton) Vent. Further documentation of this knowledge is recommended, with the goal of assessing gender differences in the use of medicinal plants in Liberia.

Dinklage, Harley, Johnston, Leeuwenberg, Voorhoeve, etc.In recent times, additional documentations of the flora were carried out in three National Forest Reserves, with some 548 species recorded, including records of three new species to science (Jongkind, 2007).It has been estimated that some 2,300 species of vascular plants occur in Liberia, although given the apparent location of two centers of endemism in the country, the actual number of plant species occurring in the country might be higher (Poorter et al., 2004).
This rich diversity of plants also features extensively in the cultural heritage of the local inhabitants, and has been a source of herbal remedies for several health problems faced by the population.However, scientific documentations of the ethnomedicinal uses of the plants have been sporadic, and very little exist on the local uses to which these plants are put.Early documentations of this knowledge date back to the early 19 th Century when a medical doctor stationed in the interior of the country documented the ethnomedicinal uses of over 200 medicinal plants among the Mano of Nimba County (Harley, 1941).Similar documentations of plant use among the Mano tribe were conducted by Adam and Adam (1970), and some four decades later, the local names and uses of over 250 important plant species in 7 communities was carried out by Marshall and Hawthorne (2013).In the Salala District of central Liberia, Orr (1968) conducted an anthropological examination of medical practices and belief systems of the Kpelle tribe, sometimes indicating the local names of plants and their ethnomedicinal uses.The actual scientific names of these plants were not reported.
Following this long hiatus, recent documentations of ethnobotanical knowledge have resumed, with assessments of Non-timber forest products (NTFP) in communities around the Sapo National Park in Liberia (Manvell, 2011).In the rainforest around the Putu Range in Grand Gedeh County, of 624 species of plants inventoried in five different habitats, 69% were of medicinal significance, with 55 species reported to include shade-bearing guild (Marshall and Hawthorne, 2012).In the Wonegizi region of Lofa County, the knowledge of local traditional medicinal practitioners was documented, producing a list of 101 species of plants in 48 families commonly used in treating 11 categories of ailments (Kpadehyea et al., 2015).
Liberia is currently going through a major transformation following the last civil war, and the need for rapid development is leading to increased exploitation of its natural resources, especially its vast resources of tropical rainforest (Blackett et al., 2009).Timber features highly in this drive, but the needs of local people are also centred on the use of important forest products such as poles, fruits, fibre and medicinal plants, among others.Like other developing countries around the world, poorly developed health care delivery systems have led to more reliance on the use of medicinal plants in most rural areas (Farnsworth and Soejarto, 1991).As local communities become speedily absorbed into the global economy, ethnomedicinal plant knowledge can quickly disappear and fears have been expressed in this regard (Lambert et al., 1997).Documenting the medicinal plant knowledge of forest dwelling communities is crucial before much of the forest disappears, and with it the extensive knowledge of traditional herbalists that interact with this rich plant biodiversity.In this regard, the main objectives of this study were to document the ethnomedicinal plant knowledge of herbalists in a forest region of Liberia, and to assess gender differences in the use of plants by male and female herbalists.

Study area
Fieldwork for documenting the medicinal plant knowledge took place in central Rivercess County of Liberia, located some 320 km from the capital city of Monrovia.Garpue Town was the main study site (Figure 1), and its population like the rest of the county is dominated by the Bassa speaking tribe of Liberia, and comprised stakeholders drawn from 7 communities located within walking distances of each other.The 7 communities included Garpue Town, Beh Town, Gbetar, Saykpayah, Poewoh Town, Bodaza and Vondeh Town, all located in the central Morweh District.Rivercess County has an area of 5,263.4km 2 and its geographic coordinates are N 5° 36 ' 23 " and W 9° 39 ' 31 " at an altitude of 84 m.The total population of the County is less than 120,000 people and 93% of them speak Bassa.It is largely a forest-dominated County and was home to three major logging activities during the past civil conflict (Blackett et al., 2009).

Data collection and analyses
We worked with traditional herbalists, identified through consultative meetings held in the chiefdom headquarter (Garpue Town), where the paramount resides.During a natural resource mapping exercise with community stakeholders, information was proffered on the heavy reliance on traditional herbalists given the lack of health facilities (Lebbie et al., 2009).These herbalists were reported to be members of the male and female secret societies, and are generally reputed for their knowledge in the use of plant remedies (Lebbie and Guries, 1995).
The number of herbalists in each community was not assessed and therefore unknown, but it was revealed through the consultative meetings that nearly every adult person possesses knowledge of the use of some plants in traditional medicine.Through further consultations with key stakeholders present at the resource mapping exercises conducted in Garpue Town, 22 practicing herbalists voluntarily consented to participate in the documentation of their ethnomedicinal plant knowledge.Using semi-structured questionnaires, we collected information on age, number of plants known and utilized, and ailments the herbalists specialized in treating.Following a brief practical guidance on how to collect specimens for taxonomic identification and herbarium vouchers, we asked herbalists to collect plant specimens known to each of them for proper scientific identification.For each plant collected and presented by herbalists, information on the ethnomedicinal uses and the parts utilized were obtained from the herbalists.No questions were asked about mode of preparation, manner of administration and local names, as herbalists had expressed concern that such information were proprietary, and we agreed not to extract such information from them.
Scientific identification and naming of medicinal plants were done on the spot, and confirmed with the aid of a field guide for woody plants known for this part of West Africa (Hawthorne and Jongkind, 2006), as well as the several volumes of the "Flora of West Tropical Africa" (Keay et al., 1954(Keay et al., , 1958(Keay et al., , 1963(Keay et al., , 1968(Keay et al., , 1972)).While every effort was made to encourage herbalists to bring plant materials with complete of morphological features (leaves, fruits/seeds and flowers) to aid in identification, on a few occasion, some herbalists brought bark specimens without leaves, flowers and fruits, and the difficulties in identification of such specimens necessitated us to discard them.Some sterile materials were insufficient to identify beyond the genus level.All specimens were tagged and with voucher numbers, are housed in the National Herbarium of Sierra Leone (SL), given the lack of a formal herbarium in Liberia.Data obtained were compiled into tables, percentages and portrayed graphically.

Gender differences and specialization in ethnomedicinal knowledge
Twenty-two ( 22) herbalists aged 27-77 years consented to participate in the documentation of their knowledge associated with ethnomedicine and the use of plants in treating various ailments.More of the herbalists were male (64%) than female (36%), with the majority of the herbalists over the age of 40 years (Table 1).The number of plants known and reportedly used by herbalists ranged between 2-40, with female herbalists knowing on average 18.1 plants more, while male herbalists knew 16.3 plants.Herbalists between the ages of 41-50 years reported knowing on average 19.1 medicinal plants, which was higher than other age categories.
Gender and age relationships have been observed in various studies involving medicinal plant knowledge.In Brazil, generally older people are reported knowing more medicinal plants than the younger people (Silva et al., 2011;Voeks and Leony 2004).For male herbalists in Nasarawa State of Nigeria, it was reported that they held more knowledge of medicinal plants than female herbalists (Ibrahim et al., 2016), although another study from Nigeria found men and women holding similar knowledge (Ayantunde et al., 2008).In three rural communities in Niger, Guimbo et al. (2011) utilizing participant observation and key-informant interviews found ethnobotanical knowledge to increase with age, but noted differences in ethnobotanical knowledge for both men and women as it related to medicinal plants.However, our study found female herbalists to know more medicinal plants than their counterpart male herbalists.Such differences can arise as a result of "limited experience", little interaction with other members of the community or due to problems with memory and forgetfulness on the part of the elderly as age sets in.The increased role often played by older women in child rearing is known to play a role in the acquisition of medicinal plant knowledge (especially over younger women).
In a study done around the Sapo National Park to document the use of non-timber forest products in adjacent communities, Manvell (2011) found women to be able to name more plants than men for the most common categories of illnesses.He attributed this to the unwillingness of the participants to share their knowledge.This is not uncommon among herbalists, and the differences in the number of medicinal plants reportedly known by each herbalist could also reflect under-reporting for fear of sharing their knowledge.We found a few of the men unwilling to share their knowledge in comparison to the women.A similar situation was observed in Sierra Leone, although in the same country, women of the sande/bondo secret societies willingly shared their knowledge of medicinal plants (Lebbie and Guries, 1995).In a review and meta-analysis of the effect of gender on medicinal plant knowledge conducted at various scales comprising national, regional and global (Torres-Avilez et al., 2016), no significant differences were apparent in the medicinal plant knowledge of men and women.Significant differences in medicinal plant knowledge were however observed at the national and continental level for both men and women.In Niger, Müller et al. (2015) found older people to be more knowledgeable about medicinal plants, with women knowing more about food plants.Given the small number of herbalists in the various age and gender categories we sampled, observed differences in reported knowledge of medicinal plants might be due purely to sample size, and possibly the unwillingness of herbalists to sometimes share their proprietary knowledge.In the Himalayas, Gupta et al. (2014) noted that herbalists (Amchis) are reluctant to disclose knowledge of medicinal plants given that this might reduce the effectiveness of the remedy.But more importantly, the knowledge of the remedies to the herbalists is what brings them "recognition", and sharing this knowledge might be seen as reducing their control over such proprietary knowledge.
Gender differentiation in ethnomedicinal knowledge and use of plants to treat certain categories of diseases was apparent, with female herbalists possessing specialized knowledge in treating children's health problems, snakebite, cholera and other medical problems related to women (Table 2).Male herbalists possessed diverse knowledge on various health problems, including broken bones, epilepsy, evil spirit, heart disease, high blood pressure, erectile dysfunction and infection of the testes, among others.Kpadehyea et al. (2015) noted also that female herbalists in the Lofa County of Liberia reported more traditional medicines that focused on children's health issues and menstrual problems than their male counterparts.Given the limited access to health facilities and drugs by these communities (Lebbie et al., 2009), women's traditional role of taking care of children could potentially help to explain their knowledge of medicinal plants associated with children's health.
One common area of specialization among some male and female herbalists is an ethnomedical problem referred to as "African sign"; a condition of ill health reported to be associated with unforeseen forces perpetuated by evil persons, "witchcraft" and or supernatural forces, for which western medicine is believed to be unable to address.It is apt to say that ill health, as perceived by the Bassa herbalists of Rivercess County is not seen entirely in the context of witchcraft or supernatural forces.Most of the ailments/diseases for which the herbalists were specialists in were not pegged on witchcraft or sorcery per se, as is often painted by ethnocentric western medical and social anthropologists (Konadu, 2008).Herbalists were quick to affirm their ability to distinguish between disease conditions in which malevolence was involved, either through witchcraft or supernatural forces, or generally as a result of some underlying etiologic or physiological condition."African sign" and "dragon spirit" or "evil spirit" were not situated in the context of etiologic agents, but rather ailments for which evil persons have caused to happen to an otherwise perfectly healthy person.Such a sickness can be cured only by herbalists skilled in traditional Bassa ethnomedicine, with western medical interventions believed to be powerless in treating it, as has been noted in some parts of Kenya (Good, 1987).In South Africa, Petrus (2011) noted the increasing role of witchcraft in the lives of the people, and cited instances where allegations of ill health resulted from the interplay of witchcraft.

Medicinal plant species and ethnomedicinal uses
A total of 112 medicinal plants, belonging to 98 plant genera and 52 families, were indicated by the herbalists as forming part of their local ethno-pharmacopoeia (Table 3).The most species rich families with at least 3 species were Rubiaceae (13 species), Euphorbiaceae (10 species), Fabaceae (11 species), Annonaceae (6 species), Apocynaceae (4 species), Asteraceae (3 species), Combretaceae (3 species), Poaceae (3 species), Costaceae (3 species) and Verbenaceae (4 species) (Figure 2).They constitute 53.4% of all medicinal plants, with the remaining 46.6% distributed among 42 families comprising of 1 or 2 species per family.In a study conducted in the Nasarawa State of Nigeria utilizing the knowledge of traditional herbalists, it was found that medicinal plants belonging to the families Euphorbiaceae, Fabaceae and Rubiaceae comprised the most species rich (Ibrahim et al., 2016).While we recorded slightly different species composition and

Figure 2 .
Figure 2. Distribution of medicinal plant families reported by herbalists.

Table 1 .
Gender and age distribution of herbalists and knowledge of medicinal plants.

Table 2 .
Gender differentiation in ethnomedicinal knowledge in treating diseases.

Table 3 .
Medicinal plants and ethnomedicinal uses reported by herbalists in the study area.