Traditional uses of the remarkable root bark hairs of Lannea schweinfurthii var. stuhlmannii (Anacardiaceae) by the Vhavenḓa, South Africa

Lannea schweinfurthii var. stuhlmannii, an African tree ranging from Sudan southwards to South Africa, has its thicker roots covered by an unusual furry layer of hair-like structures originating from the periderm. Wool-like hairs harvested from this layer, known in the vernacular Tshivenḓa as vhulivhadza, is a widely used and traded natural product in Limpopo Province, South Africa. Here we provide a detailed account of the cultural uses of vhulivhadza based on original

ethnobotanical surveys among the Vhavenḓa, as well as a review of the literature. Our findings indicate that vhulivhadza is a "magical medicine", mostly used to induce several forms of forgetfulness, both in humans and in animals. Various uses reported for L. schweinfurthii and L. alata, the latter an East African species with similar root bark hairs, suggest that the custom to use these hairs to induce forgetfulness is confined to southern Africa. The practice of taking traditional medicine to "forget something" or "to make people forget" is quite widespread in southern Africa. We discuss vhulivhadza and a few other plants used locally for this purpose, notably the mysterious sho-|õä plant of the now extinct |Xam culture, Asclepias crispa (Apocynaceae: Asclepiadoideae) and Galium tomentosum (Rubiaceae). The roots of Lannea schweinfurthii and other members of the genus are rich in phytochemicals, with at least some screenings for biological activity suggesting the presence of compounds that may affect the neurological system. In the absence of any comprehensive chemical or pharmaceutical analyses of vhulivhadza itself, the claimed memory-altering activities of this material can tentatively perhaps best be explained by psychological rather than physical (chemical) effects, but a more definite scientific explanation must await further study.

Introduction
Lannea schweinfurthii (Engl.) Engl. var. stuhlmannii (Engl.) Kokwaro [= L. stuhlmannii (Engl.) Engl.; for a detailed synonymy see Kokwaro 1986] (Anacardiaceae), a medium-sized deciduous tree, is widely distributed in Africa, from Sudan and Tanzania southwards to KwaZulu-Natal in South Africa (Kokwaro and Gillett, 1980;Coates Palgrave, 2002;Van Wyk et al., 2008Van Wyk and Van Wyk, 2013). The taxon is mainly associated with various types of savannah or dry forest (Palmer and Pitman 1973;Beentje, 1994;Lovett et al., 2006). An unusual feature of the tree is the formation of a furry layer of hair-like structures on the thick roots of the tree, especially where they merge with the trunk. Although for convenience referred to as "hairs" in the present contribution, these hair-like structures are not of epidermal origin and therefore technically not hairs in the true sense of the word (see below). Known as vhulivhadza in Tshivenḓa, these hairs are a popular and widely used traditional product in the Limpopo Province of South Africa (Mabogo, 1990;Ramovha, 1997), mainly used to induce memory loss or to make people or animals forget. The tree itself is known as mulivhadza in Tshivenḓa and as ndzivata in Xitsonga, both meaning "the tree of forgetfulness". Other vernacular names for the tree include valsmaroela (Afrikaans), false-marula (English), mmpo (Northern Sotho/Sepedi), umgabunkhomo (siSwati) and umganunkomo (isiZulu) (Van Wyk et al., 2011).
The anatomical and structural details of the unusual root bark hairs have been described by Kotina et al. (2018). These hairs turned out to be of peridermal origin, thus supporting the findings of an earlier anatomical study of similar root hairs in the East African Lannea alata (Engl.) Engl. (McQuade et al., 1970). They develop from dense clusters of phelloid cells that are scattered within a stratified phellem. The cells undergo considerable radial elongation to form hair-like radial files of elongated phelloid cells (Kotina et al., 2018).
Available information on the use of vhulivhadza by the Vhavenḓa (as cited above) is brief and often anecdotal. The aim of this paper is to provide a detailed account of the cultural uses of vhulivhadza, specifically as it pertains to forgetfulness, based on literature information and original ethnobotanical surveys. We discuss the use of this and other plant material to induce forgetfullness in South Africa, and noted some of the various uses reported for Lannea schweinfurthii and L. alata elsewhere in Africa.

Materials and methods
Ethnobotanical information was collected in several parts of the Vhembe District, Limpopo Province, the traditional home of the Venḓa people. Ethical approval was obtained from the ethics committee of the Faculty of Science, University of Johannesburg (Protocol of 13 January 2015). We strictly adhered to the ethical guidelines listed in the 2008 version of the International Society of Ethnobiology [2008]. Of particular importance is the principle of 'educated prior informed consent', which was part of the consent document, signed by all the participants prior to the interviews. The consent form gives explicit permission that the participant's name, date of birth and the traditional knowledge that he or she contributed may be used in scientific publications. The interviews were done in Tshivenḓa, the mother tongue of the first three authors and form part of a comprehensive quantitative ethnobotanical survey and PhD study by one of us (KM) at the University of Johannesburg. A total of 37 randomly selected participants from four municipalities (Makhado, Thulamela, Musina and Mutale) within Vhembe District were interviewed using a flip-file photo album showing colour images of the tree (and the product), as shown in Fig. 2 (neither the tree nor the product were named). Of the 37 participants, 10 persons (none of them traditional healers) could provide detailed information about vhulivhadza and its uses (Table 1). Seven traditional medicine ("muti") shops from the three main towns of the Venḓa area, namely Makhado (one shop), Sibasa (two shops) and Thohoyandou (four shops) were visited to check if vhulivhadza was sold there.

Review of magical uses
The Tshivenḓa name for the tree (mulivhadza) and the product (vhulivhadza) is derived fromlivhala, to forget, indicating that the plant is used to make a person forgetful and to make people forget unpleasant events (Mabogo 1990). It is also said to induce sleepiness and to make relatives forget. This magical power is ascribed to vhulivhadza, which is an important ingredient of traditional medicine (Mabogo, 1990, Hutchings, 1996, and is marketed locally. Data gathered during recent ethnobotanical surveys show that Vhulivhadza is well known and widely used in the Vembe District. Of the seven traditional medicine shops visited, four were found to stock the product ( Fig. 1) and the others were temporarily out of stock. This shows that  the product is known amongst local people and that it is still in demand. A 500 ml plastic bag of vhulivhadza is sold at an average price of R25.00 (less than two USA dollars). Kotina et al. (2018) reported that in 2016 the prevailing price for a matchbox filled with hairs was about R20.00.
From a total of 37 participants interviewed, 10 were found to know about vhulivhadza and its traditional uses (Table 1). The most knowledgeable participants were elders at an average age of 68 years. Nine main uses of vhulivhadza have been recorded.

Forgetting an unpleasant or painful event
Vhulivhadza is used to make people forget all unpleasant events (Mabogo, 1980). It is used to make a person forget his or her family members who had just passed away (i.e. to aid in the grieving process and to enhance closure after a relative died) (Mabogo, 1980). This may be done by making a decoction of the root bark of the tree, to which vhulivhadza is added, together with any root that was found to cross the grave site while digging the grave. Family members are given this decoction to drink. It is also said to protect them against a particular type of sleeping sickness known as vhulungwane in Tshivenḓa (Mabogo, 1980). Ash obtained by burning the vhulivhadza is added to soft porridge that is eaten by close family members who had just buried a relative so that they can forget the pain of death (participant M.N. Mukwevho).

Getting out of debt
The product is said to induce forgetfulness, e.g. it can be given to someone from whom a loan has been obtained (or cattle bought) but not yet paid for, so that they may forget the transaction or the outstanding debt (Coates-Palgrave, 2002). Mixed with a drink or food it is given to someone you owe money or any valuable item in order to make him or her forget about it (participants W. Madoba, N.T. Lialima, T. Mudumela and R.V. Maitakhole)

Protection and safety
Vhulivhadza is mixed with other medicine to discourage enemies from doing harm to a person by making them forget and postpone their plans (Mabogo 1980).

Enhancing marital relationships
It is an ingredient of medicines used for keeping a married woman at home by making her forget her previous social ties (Mabogo 1980 It is mixed with water or medication that is given to a patient with chronic pain or one suffering from a disease. The aim is to make him or her forget about the pain while they are still under treatment by a traditional healer, in order to facilitate the healing process (participant T.

Adoption of an orphaned child
Vhulivhadza is mixed with cooked seeds of Arachis hypogaea L.

Weaning an infant
Vhulivhadza is used to wean an infant by applying it to the mother's breast so that when the child suckles he or she will forget about milk and start to concentrate on eating solid food. The same effect can be achieved by adding the ash of burnt vhulivhadza into the baby's soft porridge so that the child, after eating the porridge, will forget suckling and concentrate on eating solid food (participants M.N. Mukwevho, R.V. Maitakhole and M. Singo).

Traditional healing
Vhulivhadza mixed with water is given to newly acquired domestic animals to drink to prevent them from straying and to strengthen their relationship with other animals at their new home while forgetting the previous home (Mabogo, 1990;Ramovha, 1997; participants T. Bohwana, S. Bohwana, W. Madoba, N.T. Lialima, N. Makhushu, P.F. Netanda and T. Mudumela). It is also generally mixed with cattle fodder that is browsed by all the animals at the same time to strengthen their relationship and to always remember their home so that they come back without the herder directing them (participant N.T. Lialima).

Medicinal and other uses recorded in southern and eastern Africa
Vhulivhadza or its uses are not mentioned by Watt & Breyer-Brandwijk (1962) and only a few traditional uses of Lannea schweinfurthii var. stuhlmannii have been recorded. A summary of medicinal and other uses that have been recorded in southern and East Africa is presented in Table 2.

Plant part(s) used and recorded uses
Reference "Root powder" (eaten in food): sedative Arnold and Gulumian, 1984 Fruit: edible Bark: used for making tea, rope and a red-brown dye; a decoction used against headache and stomach-ache Wood: used to make stools, grain pestles, and charcoal. the latter preferred by the Embu for smelting iron Beentje, 1994 "Used for medicinal and magical purposes, e.g. snake-bite" (no further details) p. 244 Boon, 2010

Preventing domestic animals from straying
Root hairs (pulverized, taken with water or gruel): tuberculosis, female sterility; Root (decoction, taken orally): asthma, dysentery, fever, stomach complaints; also anemia, diarrhea and headache Chhabra et al., 1987 "A fungus-like outgrowth from the bark of the roots actually comprises velvety hairs and is very important in traditional medicine. Said to induce forgetfulness, it can be given to someone from whom a loan has been obtained or cattle bought and not paid for. The Swazi name for this tree [umgabunkhomo, according to Van Wyk et al., 2011] means 'the tree of forgetfulness' and could derive from the fact that it features in certain ceremonies which take place when two former enemies meet and agree to forget their past quarrels. The tree is believed to harbour a benevolent spirit which is often invoked by ritual to protect and heal. A paste made from the leaves can be applied as a dressing on sores and abscesses."

Coates-Palgrave, 2002
Root (infusion or decoction): diarrhoea Gelfand et al., 1985 Bark: yields a deep red or brown dye Dale and Greenway, 1961 Review of other literature, q.v. (Watt and Breyer-Brandwijk, 1962;Kokwaro, 1976;Gelfand et al., 1985;Mabogo, 1990): Root bark (powdered, blown into the nasal cavities of a moribund patient): snakebite (citing Watt and Breyer-Brandwijk, 1962, but not found under Lannea) Hutchings et al., 1996 Bark (decoction): headache, stomach pains Leaves (infusion, as a wash): paralysis or polio Leaves (infusion, taken orally): abdominal pains in pregnant women Leaves (poultice, applied to the abdomen): to hasten childbirth Kokwaro, 1976Kokwaro, , 1983 Bark (decoction): used for making tea as a blood tonic, used by the WaPare and WaGogo for diarrhoea, stomach-ache and headache. Roots are used by the WaShambaa as a bath to bring good luck. Lovett et al., 2006 Fruits: edible, but not important as a food source Bark (soft and fleshy parts): used for tea (Maasai, Pokot), medicine for fever (Mbeere); inner bark a source of string (Maasai); fibre from bark used to make grain containers and baskets (Kamba); yields a brown dye used to decorate baskets. Brown root hairs ("wool") used for stuffing mattresses (Kamba, Tharaka, Mbeere) Trunk: carved into stools, beehives, mortars, and drums for storing honey (Kamba, Tharaka)

Maunda et al., 1999
Leaf paste (topical): ulcers (citing Bally, 1937(citing Bally, , 1938 Leaf pulp (topical): rheumatism, bruises, haematoma (citing Neuwinger, 2000Kremnitz et al., 1988 (Other information from the same sources cited here) "Used for medicinal and magical purposes" (no further details) p. 244 Pooley, 1993 Cited from Arnold and Gulumian (1984) and Van Wyk and Gericke (2000) Sobiecki, 2002 Fruit: edible, popular with birds and monkeys; seed kernels pounded, boiled with salt and consumed as a relish Bark (pounded): yields a yellowish brown dye to decorate baskets Root hairs: used for cushions, lifebelts and as an insulating material Many medicinal uses for bark, roots and leaves (no further details) In Zambia "many villages have their own Lannea tree which is used to invoke ancestral spirits, and a cutting is usually planted by the Headman when establishing a new villager. Anyone troubled by spirits or sickness is advised to plant a Lannea outside his house."  Verzar and Petri, 1987 Leaves (paste, applied topically): abscesses, carbuncles, sores (citing Bally 1937(citing Bally , 1938 "In the Balovale district of Northern Rhodesia [Zambia] the tree figures a great deal in spirit workshop" (citing Gilges, 1953) The tree figured in a case of homicide in Tanzania (not details available)

Discussion
The concept of taking traditional medicine to "forget something" or "to make people forget" is quite widespread in southern Africa. In the Cape region, the roots of two plant species are particularly prominent as "medicine to forget". These are witvergeet or witvergif, the dried and powdered root of Asclepias crispa P.J.Bergius (Apocynaceae: Asclepiadoideae) and rooivergeet or rooistorm/rooihoutjie, Galium tomentosum Thunb. (Rubiaceae). These Afrikaans names refer to the colour of the rootwhite (wit) or red (rooi) and the useto forget (vergeet). The medicinal uses of A. crispa in the Kamiesberg in Namaqualand have been described by Nortje and Van Wyk (2015). Most participants also agreed that witvergeet is a magic medicine without necessarily knowing how it is used. At least five participants confirmed that the root is chewed and spat out to make other people (or yourself) forget. It is also snuffed to "make you think clearly" or to ensure good luck in business. It is sometimes used in combination with G. tomentosum (locally called rooistorm) as a magic medicine to bring loved ones back (i.e., to ensure their safe return). The main use, however, is as traditional medicine: powdered root is snuffed to alleviate headache, while decoctions are used against a diversity of stomach ailments (including nausea, flatulence and especially stomach cramps).
Galium tomentosum appears to be the only plant species that can be linked with some certainty to the mysterious sho-|õä plant, a traditional medicine of the original !Xam people (Southern Bushman, Southern San) who once inhabited the dry Karoo region of the Cape (Hollmann, 2004: 278). The magical uses of the sho-|õä plant were recorded by Wilhelm Bleek and Lucy Lloyd when interviewing members of the |Xam in the late nineteenth century. It was said to be a men's medicine, a charm used by hunters to make the springbok "foolishly afraid", thus making it easier to get close to the animals before shooting off an arrow (Hollmann, 2004; Bleek and Loyd, http://lloydbleekcollection.cs.uct.ac.za). In interviews conducted by one of us (BEvW) with Johannes Willemse, a well-known Griqua expert on medicinal plants (Pienaar and Willemse, 2009), some interesting information came to light. According to Mr Willemse, an ointment made from rooivergeet root was traditionally applied to the bodies of San hunters when they went on springbok hunts. He stated that the ointment brought good luck to the hunter: 'the antelope will not see you and will forget about you'. This explanation was given with a subtle nuance that suggested not only forgetting but also forgiving. In a further elaboration on the uses of rooivergeet, it was stated that bathing in infusions of the root, or keeping the root in your pocket, will bring good luck, especially when you go to court. The explanation was that you will become almost invisible in the courtroom and that the judge will forget (or more likely forgive) you. It is noteworthy that a similar conclusion (of forgiveness) can be reached about witvergeet, especially when considering that witvergif has also been recorded as a common name for this plant (Nortje and Van Wyk 2015). The word vergif is ambiguous; the direct and obvious translation is "to poison" but it may possibly be a contraction of the Afrikaans word vergifnis (forgiveness). Several participants in the Kamiesberg survey agreed that the root is commonly ingested, either as an infusion, or directly chewed or eaten as a dry powder, without the usual warnings that typically accompany anecdotes about poisonous plants. The similarities between the magical uses of these unrelated plants in diverse cultures are striking. However, there are no indications that vhulivhadza is used by Venḓa people for any other purpose than making people and animals forget.
The recorded traditional uses of Lannea schweinfurthii are summarized in Table 2. Roots or root bark are used for a diversity of ailments, none of which seem to be related to the recorded uses in the Limpopo Province. There is, to the best of our knowledge, only one report of "root hairs" being used elsewhere in Africa, namely in Tanzania, where it is used to treat tuberculosis and female sterility (Chhabra et al., 1987). All the anecdotes related to sedative and memory effects originate from the Venda region (Table 2). No evidence could be found that vhulivhadza and other species used for similar purposes have sedative or mind-altering activities (but see tests for bioactivity further on).
Elsewhere in Africa, various biocultural uses have been recorded for the superficially very similar-looking root hairs of Lannea alata, a species from Somalia, Kenia and Tanzania (Royal Botanic Gardens, Kew, 1999). However, none of these uses seem to involve the induction of forgetfulness. The wool-like hairs of this species has, for example, been used by the Somali, Tharaka, Kamba and Mbeere to stuff pillows and mattresses, but no mention is made in the literature of such stuffings holding any other benefits over and above that of providing comfort (Maundu et al., 1999, Royal Botanic Gardens, Kew, 1999. These hairs (similar to vhulivhadza), are buoyant and float in watera property reminiscent of the seed floss or "kapok" obtained from some members of the Malvaceae, e.g. Ceiba pentandra (L.) Gaertn.). In this regard, it is said that a British military unit once used these hairs, at the time know under the commercial name "Floatite", as a flotation agent in lifejackets to cross rivers (Dale and Greenway, 1961).
The Anacardiaceae are known to contain skin irritants such as urushiol, the active compound in poison ivy (Rhus toxicodendron L.). Other members of the family produce similar cytotoxic and skin-irritating alkyl-and alkenylphenols but they are not known to be sedative (Wink and Van Wyk, 2008). Members of the genus Lannea are mainly used in the management of mental disorders, gastrointestinal disorders, bacterial infections, viral, infections, fungal infections and fever (for a concise review, see Okoth, 2014). In her study, Okoth (2014) isolated various secondary compounds (including novel ones) from the root and stem bark of Lannea schweinfurthii. The biological activity of these phytochemicals still needs to be explored. It is, however, noteworthy that acetylcholinesterase inhibition activity has been reported in ethyl acetate extracts from the root of L. schweinfurthii (Adewusi and Steenkamp, 2011). Similar positive acetylcholinesterase inhibitory activity was also demonstrated in methanol and dichloromethane extracts of the stem bark and root, notably the latter, of the West African Lannea barteri (Oliv.) Engl. (Koné et al., 2011). Since the cholinergic system plays an important role in the regulation of learning and memory processes, the roots of at least these two species contain compounds that may not only be effective in the treatment of neurological disorders, such as Alzheimer's disease (e.g., Anand and Singh, 2013), but may well have other memoryrelated effects.
Hitherto no detailed chemical analyses or screenings for bioactivity have been conducted on vhulivhadza, at least not in isolation from the rest of the root. Anatomically the vhulivhadza hairs were found to be tangentially extended clusters of thin-walled phellem cells with non-suberized but lignified walls; technically they comply with the definition of phelloid cells (Kotina et al., 2018). Observations on the root hairs of L. alata under the transmission electron microscope, supplemented by histochemical tests, indicated a heavy lipid core surrounded by a cellulose sheath. Paper chromatography of a methanol-chloroform extract of the cork and its associated wooly covering of hairs in the latter species showed the presence of abundant sterol and carotenoid compounds (McQuade et al., 1970). However, a lipid core has not been reported in vhulivhadza (Kotina et al. 2018), although it could have been overlooked.
Several southern African members of the Anacardiaceae, Apocynaceae and Rubiaceae have been recorded as having psychoactive uses (Sobiecki, 2002) but there appear to be no psychoactive compounds (such as alkaloids) known from these plants. In Europe, Galium odoratum L. is used in traditional medicine and is known to have sedative effects, which are associated with coumarins (Van Wyk and Wink, 2017). The Apocynaceae are known to contain heart glycosides and chemically related pregnane glycosides with analgesic and appetitesuppressant effects (Van Wyk et al., 2009) but the main chemical compounds of Asclepias crispa have apparently not yet been studied. Except for the acetylcholinesterase inhibitory activity found in some Lannea root extracts mentioned above, no obvious links seem to exist between the chemistry of these magic medicines and their supposed sedative or memory-altering activities, suggesting that their use can perhaps be best explained by psychiatric and psychological principles. It should be noted, however, that lemons and limes were once also "magic medicines", until their activity against scurvy could be rationally explained by the discovery of Vitamin C, more than 200 years later (Van Wyk and Wink, 2017). At this stage treatment with vhulivhadza appears to have psychological rather than physical (chemical) effects but it is perhaps prudent to keep an open mind. Further research is needed to explore a possible scientific rationale behind the unusual and interesting uses of vhulivhadza.