This research was performed in four villages adjacent the boundary of Udzungwa Mountains National Park in the Kilombero River plain of Tanzania. The area adjacent the villages is characterized by self-consumption agriculture, with a population that is on average poor, still very tied to traditions and almost entirely unaffected by modernization and technology. The aim of the present study was to investigate and record local knowledge regarding the use of wild and traditionally cultivated plants used for traditional medicine and for other everyday purposes (e.g., food, fibers and timber).
Methods
Ten traditional local healers, with solid botanical knowledge, were interviewed between June and August 2014 by means of semi-structured questionnaires. For each mentioned plant species, the Swahili folk name and, when possible, the classification by family, genus and species was recorded as well as the part of the plant used, the preparation method and the main uses (medicine, food or others).
Results
In total 196 species were mentioned of which 118 could be botanically classified. The identified species belong to 44 different botanical families, with that of the Leguminosae being the most representative (24 species). The plants were mostly used as medical treatments (33.3% of the species) and foods (36.8%), and to produce wood and fibers (19.4%).
Conclusion
The present study revealed that numerous plant species are still essential in the everyday life of the tribes living in Kilombero Valley. Most of the plants were usually harvested in the wild, however, after the creation of the Udzungwa Mountains National Park, the harvesting pressure has become concentrated on a few unprotected forest patches. Consequently, many useful species are becoming increasingly rare with the risk of losing the connected botanical and traditional knowledge. The present study may, therefore, contribute to record the ethnobotanical knowledge held by these populations, in order to preserve this valuable richness for future generations.
The online version of this article (doi:10.1186/s13002-017-0146-y) contains supplementary material, which is available to authorized users.
Background
Synthetic materials replaced nowadays many traditional plant-derived products having an increasing impact on the ethnobotanical culture of traditional societies. However, both wild and cultivated plants still remain vital to many aspects of traditional life [1]. In particular, plant species provide humans many type of building materials such as timber, poles and fibers [1‐3]. Timber, the major forest product, has a considerable importance in the construction of temporary shelters, permanent homesteads and fences within the traditional societies [1], stems and leaves of grasses and palms are used in roof covering [2]. Plant parts have also additional uses in traditional arts and handicrafts including tool handles, cooking utensils, baskets, cordage and textiles [1, 4]. Likewise, plant extracts are sources of dyes, gums, latex, waxes, resins and adhesives [1, 2]. The most important uses of plants in developing countries (such as Tanzania) are however for fuel and medicine [5, 6].
In Tanzania, about 69% of the population lives in rural areas [7] where forest resources are central to their livelihood. Furthermore, according to the World Health Organisation (WHO), up to 80% of the population in developing countries depend on locally available plant resources for their primary healthcare [8]. In Tanzania, traditional medicine provides health care and support to over 60% of the rural population [9, 10]. This trend is mainly due to the strong attachment to traditions and spirituality and to the greater access, with respect to conventional medicine, to healers inside villages that provide low cost treatments [11]. The traditional medical treatments are mainly based on herbal remedies, using sometimes many different species mixed together [4, 12]. Except for a few plant species that grow inside or close to the villages, most of the used species are collected in forest areas [13].
Anzeige
Almost all the remaining forests in Tanzania are now found in protected areas, but in a few locations, with lower human population density, some unprotected forest patches [14] still remain. Public forest lands are freely available for use, whereas the exploitation of natural reserves is restricted by the issuing of licenses. Most of the unprotected forest land comprises miombo woodland (by the Swahili name of the common genus Brachystegia) which provides food, fuel, construction materials and medicines but is seriously threatened by overexploitation [15].
In Kilombero Valley (Morogoro region, where the present study was located, Fig. 1) deforestation was caused by the need to obtain land for agriculture and for the establishment of teak (Tectona grandis L.f.) and eucalyptus (Eucalyptus globulus Labill) plantations, as well as by charcoal production from cutted trees. Nonetheless the remaining lowland forest are still not protected unlike the neighbouring Udzungwa Mountains where a strong protection is carried out on the entire elevational range of the forest [14].
Fig. 1
Study area. The enlargement shows the location of the four villages where the interviews took place
×
For years, local healers could bypass the restrictions for access to National Parks, but given the increasingly strict rules, they have lately been forced to change their places of collection with a serious impact on everyday life. In fact, the knowledge and experience of each traditional healer are deeply linked to the place where he/she learned and practiced plant collection over the years. There are now few forest areas in Kilombero Valley that can provide therapeutic plants. These are located far from the villages, and some of the collection methods, such as decortication, could be extremely impactful when carried out in small areas, making the plants unusable after a few years.
Since the founding of Udzungwa Mountains National Park, more than 24 years ago, there has been a depletion of the traditional medical culture, due to the forced abbandonement of familiar areas of collection, as well as the progressively more difficult transmission of knowledge to and training of young healers. Finally, the cost of traditional medicine is now starting to grow, causing a significant problem for people who have always relied on this method for their healthcare [11]. Since the 1970s, international health policy began to take interest in traditional medicine in Tanzania [11]; with the Traditional and Alternative Healthcare Practice Act 2002, the government recognizes traditional medicine as being important in the healthcare of its people. However, despite legislation being in place, not much progress has been made in the documentation and evaluation of the vast resource of medicinal plants used by traditional healers [16] and no actions have been taken to solve problems related to plant gathering practices.
Anzeige
Previous ethnobotanical studies have been conducted in Tanzania with the main purpose to investigate ethnomedicinal knowledge of local healers [9, 12, 13, 16‐18], but only few have been carried out in the Morogoro region [5, 19, 20]. Some studies were also aimed at obtaining general ethnobotanical knowledge, including plant uses other than medicinal ones [5, 21].
The present study was carried out in four villages located between the agricultural area of Kilombero Valley and Udzungwa Mountains National Park (Morogoro region) (Fig. 1), in which the people obtain most of the raw materials for every day life and most medicinal plants from the forest environment [19]. Until 1992, year of the establishment of the Udzungwa Mountains National Park [22], the inhabitants of the area had free access to the forest and were able to dispose of its resources in an easy and sometimes indiscriminate way. Successively, restrictions have been introduced to limit the collection of plants inside the park, until the complete ban since 2011. Despite the efforts, made by the Authority managing the park and by non-profit organizations to educate the inhabitants of neighbouring villages to become independent from the forest, the total prohibition of using the park had a profound effect on people’s lifestyle and most of the traditional medicine practices.
The aim of the present research was to collect data about plants, both cultivated and wild, used for traditional medicine and for other everyday purposes (e.g., food, fibers, timber), in order to preserve an important endangered part of the local cultural heritage. In fact, if in general ethnobotanical knowledge is being progressively lost all over Africa due to modernization and globalization, this is even more so in the Udzungwa Mountains, where all the activities closely related to the use of plant natural resources are limited by the strict rules and regulations of the National Park.
Methods
Study area
The study was carried out in four villages (Mangula, Muaya, Ichonde, Kisawasawa), located close to the southern limit of the Udzungwa Mountains National Park (Morogoro region, Tanzania), in the large agricultural plain of the Kilombero river (Fig. 1). The study area, is dominated by a dry climate, with 750 mm of average annual rainfall. The climate is defined bi-seasonal and the annual variations are determined by the monsoons coming from the Indian Ocean. The hottest period starts in December and lasts until March. During this period, rainfall is abundant and the average maximum temperature is in December around 26.9 °C. The rain season reaches its peak in April. The dry and fresh season begins in May and lasts until October. The cooler months are June and July with an average temperature of 21.5 °C (https://it.climate-data.org/location/3040/). The vegetation of the area is mainly represented by Miombo woodlands, a subtropical formation typical of semi-arid and arid climate. Miombo is the Swahili word for the Brachystegia genus, which is the dominant tree in this natural environment together with Julbernardia and Isoberlinia, of the subfamily Caesalpinioideae. Artificial grassland and shrublands are also present due to human activities [23].
The lack of industrialization, the remoteness from urban centers, the proximity to mountains and the generalised poverty make this location a perfect nursery for the growth and preservation of ethnobotanical knowledge. In fact, in this area the effects of globalization are still very weak and the people are usually closely tied to their traditions.
In these communities, agriculture is the main economic activity, together with some animal husbandry often finalized to self-consumption, and the cultivated species are not numerous [5, 6]. Beside rice and corn, many other vegetables are grown, mostly belonging to the Solanaceae, Brassicaceae, Amaranthaceae and Cucurbitaceae families. Fruit trees, such as Prunus persica (L.) Batsch, Persea americana Mill., Mangifera indica L. and Annona sp., are also present on farms and in gardens [5]. The people of these villages depend on the Miombo forest not only for food, but also for the supply of wood and coal, that remain the most widely used fuels for cooking, brick making and woodworking. Other products that derive from the forest are the majority of natural fibers, for the production of ropes, baskets and rugs, and most of the medicinal plants [19].
Selection of the informants and interview method
In general, ethnobotanical studies performed for cognitive and preservative purposes of local knowledge aim at collecting as much information as possible [24]. However, when conducting interviews, it is sometimes useful to select a preferencial topic to avoid wasting time, but above all, to investigate and preserve a specific and sometimes mostly endangered type of knowledge.
In the present study, beside the collection of general ethobotanical information, the attention was focused on plant medicinal use. The selection of candidates for interviews was performed with the collaboration of the Mazingira Association (http://www.mazingira.net/) that runs environmental education projects in the study area and operates in close contact with the resident population. Given the limited extension of the study area and the hesitancy of some local healers in sharing their knowledge, it was possible to interview only ten people.
Anzeige
The interviewes were carried out between June and August 2014, to ten candidates belonging to seven different tribal groups (Hehe, Pare, Chaga, Pogoro, Luguru, Mndamba, Mndegereko) with four people belonging to the Hehe group, predominant in this territory [12].
Each informant was interviewed individually for one or more times, according to his amount of knowledge. The interviews were always held in familiar places, to make it easier for the interwiewee to find the species with whom he/she is familiar. Each interview was conducted in Swahili language and mediated by an interpreter (Swahili-English) to allow the respondent to easily express his/her knowledge. For completeness and standardization of collected information, interviews were conducted by means of semi-structured questionnaires [25] (Additional file 1). The questionnaires were specifically developed for the purposes of the present study, based on a previous ethnobotanical research [26].
The interview consisted of three steps. At the first meeting, interviewer and informant were introduced to each other, the objectives of the study were explained in detail and the informed consent of the candidate to the interview, filming and taking photographs was acquired (Additional file 1). In a second phase, the personal information of the respondent, such as age, tribal group, profession and education level, was collected through a semi-structured questionnaire. Finally, the ethnobotanical knowledge was investigated. For each mentioned plant species, the informant was asked to provide information regarding the parts of the plant used, the method and period of harvesting, possible uses (e.g., food, fiber production, timber, spiritual uses, etc.) and whether the plant is still commonly used. Although a pre-structured questionnaire was used for the collection of this information, the candidate was left to speak freely and only at the end of the discussion specific questions were addressed to complete the data. Each interview was itinerant and took place under the guidance of the candidate, who was moving within the territory from which he/she usually collects plants, to directly show the plant species. The interviews usually took place in the morning before lunch and lasted between 3 and 4 h. After each interview, the candidate was payed 5000 Tsh (about 2.10 Euros) as compensation for the time spent. In addition, candidates received a paper, written in English and Swahili, with the purposes of the study to which they had just contributed. During the interviews, specimens were collected for an herbarium (Fig. 2a), after having acquired permission from the interviewee for plants located on his/her private property. Plant samples were never collected inside protected areas, therefore, when it was not possible to collect herbarium samples, detailed photographs of the plant species and of the used parts were taken.
Fig. 2
Plant sample collection and numbering. aSolanum incana specimen ready to be dried and pressed; b example of collection number
×
All material was immediately tagged and marked by a progressive code of five numbers (Fig. 2b, Table 1): the first two digits indicate the respondent, while the following three digits identify the plant species. The plants (both in the form of herbarium samples and/or photographs) were firstly classified on the basis of diagnostic characters and validated by using the correspondence with the folk name provided by the informant (Table 1). All the plant samples were delivered to the Department of Botany of Dar-es-Salaam University where voucher specimens were collected and deposited. The plant species were classified following the standard botanical nomenclature according to The Plant List (http://www.theplantlist.org/).
Table 1
List of plants mentioned by informants in the study area and botanically classified with at least the botanical family name
Collection number
Family
Genus and species
Number of citations
Folk name
Growing habit
Wild\ cultivated
Main uses
Parts used
Cured diseases
Other uses
08003
Acanthaceae
Hygrophila auriculata (Schumach.) Heine
*
Mbigiri
herb
W
M
leaves
wounds
03003
Amaranthaceae
Amaranthus sp.
*
Mchicha
herb
C
F
plant
01005
Anacardiaceae
Schinus sp.
*
Mpilipili
tree
W
F
fruit
08008
Anacardiaceae
Sclerocarya birrea (A.Rich.) Hochst
*
Mbwegere
tree
W
M
bark
gastrointestinal
02009
Annonaceae
Annona muricata L.
*
Mstafeli
tree
C
F
fruit
07012
Annonaceae
Annona reticulata L.
*
Topetope
tree
C
F
fruit
01013
Apocynaceae
Landolphia kirkii Dyer
*
Kibanalomo
climber
W
F
fruit
01020
Apocynaceae
Saba comorensis (Bojer ex A.DC.) Pichon
*
Lingombe
climber
W
F
fruit
01033
Apocynaceae
Tabernaemontana pachysiphon Stapf
**
Mkomba, Mlowolowo
tree
W
M
roots, leaves
gastrointestinal
01010
Apocynaceae
unidentified
*
Kihongola
shrub
W
R
branches
knives, handles
02015
Araceae
Colocasia esculenta (L.) Schott
*
Magimbaji
herb
C
F
roots, leaves
02016
Araceae
Colocasia sp.
*
Magimblima
herb
C
F
roots
05030
Araceae
Philodendron sp.
*
Mtambala panya
herb
W
M
leaves
respiratory
02017
Arecaceae
Elaeis guineensis Jacq.
*
Mchikichi
palm
C
F
fruit
01021
Arecaceae
Phoenix reclinata Jacq.
*
Ukindu
palm
W
R
leaves
baskets, mats
01039
Arecaceae
unidentified
*
Msalisi
palm
W
F
leaves
01009
Asparagaceae
Asparagus flagellaris (Kunth) Baker
*
Mwinika
herb
W
F
plant
08007
Bignoniaceae
Kigelia africana (Lam.) Benth
***
Mfungutua, Mfumbili
tree
W
M, O
bark, fruit
pain and inflammations, gastrointestinal
03002
Brassicaceae
Brassica sp.
*
Chinese
herb
C
F, M
leaves
gynaecological, andrological and urinogenital
03011
Brassicaceae
unidentified
*
Figiri, Leshuu
herb
C
F, M
leaves, plant
pain and inflammations, cardio-circulatory
04015
Caricaceae
Carica papaya L.
*
Mpapai
tree
C
F
fruit
01025
Cecropiaceae
Myrianthus holstii Engl.
*
Mfusa
tree
W
F
fruit
01023
Clusiaceae
Allanblackia stuhlmannii (Engl.) Engl
*
Mkanyi
tree
W
F
fruit
01003
Combretaceae
Combretum sp.
*
Mlama
tree
W
R
plant
charcoal, traditional beehives
06006
Combretaceae
Terminalia catappa L.
*
Mkungu
tree
C
F, R
fruit, plant
firewood
04006
Compositae
Bidens pilosa L.
*
Mashona nguo
herb
W
F
leaves
05024
Compositae
Emilia coccinea (Sims) G.Don
*
Muelishi
herb
W
F
leaves
01016
Compositae
Lactuca inermis Forssk.
**
Mchunga
herb
W
F
leaves
01007
Compositae
unidentified
*
Jungujungu
herb
W
M
leaves
wounds
05016
Compositae
unidentified
*
Mnyamgoha
herb
W
M
plant
gynaecological, andrological and urinogenital
05023
Compositae
unidentified
*
Munosa
herb
W
M
flowers
eyes disesaes
07004
Compositae
unidentified
*
Mganagana
herb
W
M
plant
typhus
04003
Convolvulaceae
Ipomoea batatas (L.) Lam.
**
Kiazi kitam
herb
C
F
roots
02010
Convolvulaceae
Ipomoea sp.
*
Matembele
herb
C
M, F
leaves
weakness and faints
08001
Convolvulaceae
unidentified
*
Kaberega
herb
W
M
leaves
gynaecological, andrological and urinogenital
02014
Crassulaceae
Kalanchoe sp.
*
Msharif
succulent
C
M
leaves
gastrointestinal, cardio-circulatory
04005
Cucurbitaceae
Cucurbita sp.
*
Majani ya Maboga, Maboga
herb
C
F
leaves
01029
Cucurbitaceae
Momordica foetida Schumach.
*
Delega
herb
W
F
leaves
04013
Cucurbitaceae
Telfairia pedata (Sm.) Hook.
*
Mkweme
climber
C
F
seeds
03005
Cyperaceae
unidentified
*
Makangaga
herb
W
R
plant
roof cover
02020
Dracaenaceae
Dracaena fragrans (L.) Ker Gawl.
*
Msae
shrub
C
O
plant
fence, decoration
01019
Dracaenaceae
Dracaena mannii Baker
*
Mshindamaji
shrub
W
M
leaves, bark
gastrointestinal, parasites, aphrodisiac
01004
Ebenaceae
Diospyros loureiroana G.Don
*
Mdaa, Nyakatitu
shrub
W
O
plant
colorant
01035
Euphorbiaceae
Bridelia micrantha (Hochst.) Baill.
*
Mwiza
tree
W
R, O
log, bark
roof frames, colorant
01012
Euphorbiaceae
Jatropha sp.
*
Mtowo
shrub
W
R
bark
ropes and strings
02022
Euphorbiaceae
Manihot esculenta Crantz
***
Kisamvu
shrub
C
F
leaves, roots
06002
Lamiaceae
Gmelina arborea Roxb.
*
Mfudufudu
tree
C
R
log
furniture
07011
Lamiaceae
Leonotis nepetifolia (L.) R.Br.
*
Kitengetenge
herb
C
M
leaves
malaria, hernia, typhus
05040
Lamiaceae
Ocimum gratissimum L.
*
Mfumbeza
herb
W
M
plant
incontinence
02013
Lamiaceae
Ocimum tenuiflorum L.
*
Mvumbasi, Mlumbasi
shrub
C
M
leaves
teeth an gums
insect repellent
02019
Lamiaceae
Tectona grandis L.f.
*
Mtiki
tree
C
R
log
furniture
04002
Lamiaceae
unidentified
*
Mwidu
herb
W
F
leaves
05005
Lamiaceae
unidentified
*
Nyaka bondwa
herb
W
M
roots
snake bites
05025
Lamiaceae
unidentified
*
Muhesita
herb
W
M
plant
children incontinence
08005
Lamiaceae
unidentified
*
Mjekijeki
herb
W
M
leaves
wounds
09012
Lamiaceae
unidentified
*
Uftapori
herb
W
M
leaves
malaria
01040
Lamiaceae
Vitex doniana Sweet
****
Mcoga, Mfulu
tree
W
M, F, R
bark, leaves, fruits, log
weakness and faints
spoons, carved objects
09003
Leguminosae
Abrus precatorius L.
*
Ufambo, Kizunguzungu
climber
W
M
leaves
weakness and faints
05010
Leguminosae
Acacia sp.
*
Mtalula
tree
W
M
leaves, roots
gynaecological, andrological and urinogenital
07001
Leguminosae
Acrocarpus fraxinifolius Arn
*
Mkalati
tree
W
M
bark
gastrointestinal
05038
Leguminosae
Albizia schimperiana Oliv.
*
Msere
tree
W
R
branches
handles
05039
Leguminosae
Bauhinia petersiana Bolle
**
Myegea, Msegese
tree
WC
M
bark
respiratory, diabetes
03008
Leguminosae
Brachystegia sp.
*
Miombo
tree
W
R, O
plant, pollen
charcoal, bee plant
04008
Leguminosae
Cajanus cajan (L.) Millsp.
***
Mbaazi
shrub
C
M, F, R
leaves, seeds, plant
teeth and gums, otitis
firewood
05017
Leguminosae
Crotalaria sp.
*
Muvele
herb
W
M
leaves
headaches
05012
Leguminosae
Dalbergia melanoxylon Guill. & Perr.
*
Mpingo, Mningo
tree
W
O
log, leaves
carved objects, furniture, ritual against snakes
01011
Leguminosae
Entada sp.
*
Lifute
climber
W
P, O
leaves, bark
strong detergent
01037
Leguminosae
Erythrophleum suaveolens (Guill. & Perr.) Brenan
*
Mbaraka, Muhehe
tree
W
R
log
furniture
09010
Leguminosae
Piliostigma thonningii
*
Msegete
tree
W
M
leaves
gastrointestinal, gynaecological, andrological and urinogenital
01001
Leguminosae
Pterocarpus angolensis DC.
**
Mninga, Mnynga
tree
W
R, M
log, bark
gynaecological, andrological and urinogenital
furniture
05006
Leguminosae
Senna siamea (Lam.) H.S.Irwin & Barneby
*
Msonobari, Mjohoro
tree
WC
M, R
roots, plant
firewood
10003
Leguminosae
Tamarindus indica L.
**
Mkwaju
tree
WC
M, F
leaves, fruit
respiratory, gastrointestinal
parasites
01043
Leguminosae
unidentified
*
Likunde
herb
W
F
flowers
04009
Leguminosae
unidentified
*
Linyala
shrub
W
F
leaves
04014
Leguminosae
unidentified
*
Fiwi
climber
C
F
seeds
05008
Leguminosae
unidentified
*
Mfuna
herb
W
M
plant
weakness and faints
05015
Leguminosae
unidentified
*
Mugoba
tree
W
M
leaves
respiratory
05029
Leguminosae
unidentified
*
Mkalangangumbi
herb
C
O
leaves
ritual to increase chicken growth
08006
Leguminosae
unidentified
*
Liwowo
shrub
W
F
leaves
08010
Leguminosae
unidentified
*
Msawere
climber
W
M
roots
headaches
09013
Leguminosae
unidentified
*
Limbatamba
shrub
W
M
roots, leaves
cardio-circulatory
05046
Liliaceae
unidentified
*
Muheri
herb
W
M
plant
gastrointestinal
01034
Logoniaceae
Anthocleista grandiflora Gilg
*
Mbala
tree
W
O
leaves
poisons
04012
Malvaceae
Abelmoschus esculentus (L.) Moench
*
Bamia
herb
C
F
fruits
02021
Malvaceae
Hibiscus sabdariffa L.
*
Karkade
shrub
C
M
leaves, fruits
cardio-circulatory
05019
Malvaceae
Hibiscus surattensis L.
***
Likakanapi, Mnyanyani
herb
W
M
leaves
eyes diseases, gastrointestinal
02008
Meliaceae
Cedrela odorata L.
*
Msenderela
tree
C
R
log
gastrointestinal
furniture
02007
Meliaceae
Khaya anthotheca (Welw.) C.DC.
*
Mkangazi
tree
C
R
plant
anemia
furniture, firewood
06004
Mimosaceae
Acacia auriculiformis Benth.
*
Msegerea, Mzanzibari
tree
C
R
plant
furniture, firewood
01042
Mimosaceae
Parkia filicoidea Oliv.
*
Mnieze
tree
W
F, R
fruit, log
furniture, building materials
02003
Moraceae
Artocarpus heterophyllus Lam.
*
Fenesi
tree
C
F
fruits
09011
Moraceae
Ficus sycomorus L.
*
Mkuyu
tree
W
M, O
bark, leaves
weakness and faints, wounds
ritual against evil eyes
05054
Moraceae
Milicia excelsa (Welw.) C.C.Berg
*
Mvule, Myange
tree
W
M, R
bark, log
furniture
01036
Moraceae
Treculia africana Decne. ex Trécul
*
Msaia
tree
W
F
fruits, seeds
weakness and faints
02004
Moringaceae
Moringa oleifera Lam.
*
Mlonge
tree
C
M
leaves, seeds
malaria, weakness and faints
03012
Musaceae
Musa x paradisiaca L.
*
Mgomba
herb
C
F, R
fruit, log
strings
06003
Myrtaceae
Eucalyptus tereticornis Sm.
**
Mlingoti, Mkalatusi
tree
C
R, M
log, bark, leaves
respiratory
poles
02006
Myrtaceae
Psidium guajava L.
**
Mpera
tree
C
M, F
leaves, fruit
gastrointestinal
01027
Myrtaceae
Syzygium guineense (Willd.) DC.
*
Mzambarau, Mvenge
tree
WC
F
fruit
05028
Nyctaginaceae
Bougainvillea spectabilis Willd.
*
Mpropes
shrub
C
M, O
leaves, flower, plant
parasites
decoration, acarus repellent
02005
Oxalidaceae
Averrhoa bilimbi L.
*
Mbilimbi
tree
C
F
fruit
01017
Piperaceae
Piper capense L.f.
*
Likundukundu
shrub
W
F
fruit
10008
Poaceae
Cymbopogon citratus (DC.) Stapf
*
Mchaichai
herb
C
F
leaves
poles
03004
Poaceae
Oxytenanthera abyssinica (A.Rich.) Munro
*
Mianzi ya ulanzi
herb
C
F, R
sap, log
poles
03006
Poaceae
unidentified
*
Magugu
herb
W
R
plant
roof cover
03007
Poaceae
unidentified
*
Magugu
herb
W
R
plant
roof cover
01014
Rubiaceae
Uncaria africana G.Don
*
Likamanda
climber
W
F
plant
02024
Rutaceae
Citrus limon (L.) Osbeck
*
Lemon tree
tree
C
F
fruit
02018
Rutaceae
Citrus nobilis Lour.
*
Tangerine
tree
C
F
fruit
01041
Sapotaceae
Synsepalum msolo (Engl.) T.D.Penn.
*
Msambisa
tree
W
F, R
fruit, log
poles and handles
03001
Solanaceae
Capsicum chinense Jacq.
**
Mpilipili
herb
C
F, O
fruit
repellent
10004
Solanaceae
Nicotiana tabacum L.
*
Tumbaco
herb
C
O
leaves
cigars
07009
Solanaceae
Physalis peruviana L.
*
Songosongo
herb
C
M
leaves
respiratory
01018
Solanaceae
Solanum incanum L.
**
Mdulele, Mtula
shrub
W
M
fruit, roots
parasites, bites, gastrointestinal
06001
Solanaceae
Solanum melongena L.
*
Ngogwe, Nyanyachungu
herb
C
F
fruit
03010
Solanaceae
Solanum sp.
*
Mnafu
herb
C
F
leaves
02023
Sterculiaceae
Theobroma cacao L.
*
Cacao
tree
C
F
fruit, seeds
05026
Verbenaceae
Duranta erecta L.
*
Msekela
shrub
C
O
leaves, roots
ritual
Frequency: * one citation, ** two citations, *** three citations, **** four citations
C cultivated species, W wild species, WC both wild and cultivated species
M medicinal use, F food use, R production of raw material, O other uses
Anzeige
Despite all efforts, 78 plant species could not be classified given the lack of samples and sometimes of diagnostic characters in the specimens. The unidentified plants are listed in the Additional file 2 using just the vernacular name given by the informant. Even tough the interviewees exactly described the medical proprieties and other uses of these plant species, they were not included in the following data processing.
Results and discussion
Informants
In total ten informants were interviewed, three women and seven men, aged between 31 and 86 years, with a mean age of 53 and a median of 53. Six respondents were over 50 years old. Ethnobotanical knowledge was not equally shared between the two genders and the average number of quoted species was 13.7 for men and 7.3 for women. On average, male informants reported 5.8 food plants and female 5.6. Similarly, the number of medicinal species cited was 5.7 for males and 6.0 for females. This reflects the fact that traditional ethnobotanical knowledge equally passed on through both the male and female line.
The informants were traditional healers as first or second job and all practiced farming. The respondents belonged to different ethnic groups: four were of the Hehe tribe, the dominant tribal group in the investigated area, while the other six candidates were one each of the Pare, Chaga, Pogoro, Luguru, Mndamba, Mndegereko tribes. On average education level was low, with nine candidates having attended just primary school and only one who also attended secondary school.
Data on plant species
Overall 196 different plant species traditionally used in the four villages of the study area were mentioned. For 118 samples, at least the family and, in most cases, the genus and species were idientified (Table 1), while for 78 plants only the folk name was available despite the efforts of classifying them (Additional file 2). Taking into consideration similar researches conducted in study areas neigbouring the Kilombero valley, the percentage of identified species (Table 1) in common with previous studies was 15.3% respect to those detected by Amri et al. [5], 20.3% respect to Shangali et al. [19] and 5.9% respect to Chrispin et al. [20].
Anzeige
Most of the plant species belonged to the family of Leguminosae (24), followed by Lamiaceae (11), Compositae (7) and Solanaceae (6) (Fig. 3). This result is in agreement with similar studies carried out in the Morogoro region [18] and other areas of Tanzania, where Leguminosae, Compositae and Solanaceae were among the most aboundant families [13, 16, 18]. In comparison with previous studies [13, 16, 18], the present data revealed a large presence of Lamiaceae, probably due to the widespread coltivation of this plant family (e.g., Ocimum tenuiflorum L., O. gratissimum L.) around the villages. Data evidenced the absence of plants belonging to the Rubiaceae family, as instead previously detected in other studies in the Morogoro region [18]; this was most probably due to the lack of forest areas nearby the studied villages and to the fact that most plants were collected in grassland and shrub areas, where this family is rarely present. Of all recorded species, 38.1% were trees, 38.1% herbs, 13.6% shrubs, 6.8% climbers, 2.5% palms and 0.8% succulent plants, which is again in accordance with previous studies which detected a large prevalence of tree species [5, 13]. Of the 118 identified species (Table 1), 67 were collected in the wild, 47 were cultivated and 4 were both cultivated and spontaneous, such as Tamarindus indica L. Overall, 52% of the reported useful species were exotic plants, while the remaining 48% were native plants.
Fig. 3
Main botanical families of plant species mentioned by informants in the Kilombero Valley
×
Ethnobotanical knowledge is very diverse among the various tribes and for this reason multiple citations of plants by different healers are usually rare [12] (Table 1). The most cited plant is Vitex doniana Sweet (by 4 respondents), commonly used to prepare a tonic and energizing infusion. Manihot esculenta Crantz, Kigelia africana (Lam.) Benth., Cajanus cajan (L.) Millsp. and Hibiscus surattensis L. were cited by 3 respondents, but while the first is only used as food, the other three species are used for many purposes, including food, fuels, medicine and rituals (Table 1).
Uses of cited species
Most of the identified species were used for food purpose (36.8%), and medicinal use (33.3%), followed by production of raw materials, such as wood and fibers (19.4%), and ritual use (3.5%) (Fig. 4). When considering the totality of the mentioned species (196, Table 1 plus Additional file 2), the medicinal species represented the majority (45%), which is in agreement with other studies carried out in the Morogoro region [5].
Fig. 4
Different uses of the plant species mentioned by informants and botanically classified in the study area
×
Of the identified plants (Table 1), 79.7% have only one use, 18.6% have two uses (e.g., Psidium guajava L., used as food and medicine) and 1.6% have three different uses (e.g., C. cajan L. Millsp, used as medicine, food and fuel). Some of the mentioned plants (14 species among which V. doniana, Synsepalum msolo (Engl.) T.D.Penn., Parkia filicoidea Oliv. and Milicia excelsa (Welw.) C.C.Berg) are highly valued trees, not only as food (for their edible fruits) and medicines, but also as firewood and timber. This fact is causing a fast depletion of the number of individuals of these wild species due to the indiscriminate cutting down of the trees.
Medicinal use
The parts of the plants (Fig. 5a) mainly used for the preparation of herbal remedies were leaves (50%), bark (16.7%, Fig. 6a), roots (13.3%), whole plant (10%), fruits (6.7%) and other parts like sap or flowers (3.3%). A similar distribution was found by other studies in Africa [5, 13, 16, 18], with in general leaves representing the most frequently used plant part for medicine. Conversely, other studies reported roots as the most used part in preparing drugs [12, 27].
Fig. 5
Plant species for medical treatments. a Used parts of the plants; b preparation methods
Fig. 6
Plant different uses. a Stand of a local healer with numerous barks for sale; b fruits of Landolphia kirkii Dyer, a wild liana; c the bark of Brachystegia sp. used to tie together the elements of traditional houses; dDuranta erecta L., a ritual species, used against misfortune
×
×
Most of the medicinal plants mentioned by the informants were usually harvested in the wild (32 species), while only few were cultivated (13 species). Therefore, plant harvesting methods have a deep impact on the natural ecosystem. In fact, while the collection of leaves somehow preserves the integrity of the plant, the excavation of roots and decortication, have extremely deleterious effects on plant individuals leading to their premature death. According to the opinion of the informants, many of the medicinal species subjected to such practices are at present seriously threatened and are becoming increasingly rare in their habitats. This triggers a vicious cycle of an even larger exploitation of the remaing specimens, which will accelerate their disappearance as already reported by Amri et al. [5] in other Morogoro region sites.
In 71.4% of cases, the mentioned medicinal plants were indicated for the treatment of a single disease, 22.5% of the species were used to cure two diseases, while the remaining 6.1% were used in the treatment of three or more diseases (such as Dracaena mannii Baker, Leonotis nepetifolia (L.) R.Br., Solanum incanum L.). Among the most cured diseases were gastrointestinal pathologies (diarrhea, vomit, stomach ache) cured by 11 species, weakness and faints (7 species), gynaecological, andrological and urinogenital disorders (erection, infertility, bleeding losses) cured by 7 species, respiratory diseases (cough, cold) (6 species), parasites (6 species), cardio-circulatory problems (4 species) and wounds (3 species) (Table 2). Other studies showed intestinal pathologies [5] and also wounds, respiratoty, urinogenital and cardio-circulatory (e.g. hypertension) disorders as those most frequently treated with medicinal plants [18].
Table 2
Type of diseases cured by plants botanically identified in the area of study (see Table 1)
Disease
Number of species suitable for treatment
Gastrointestinal
11
Weakness and faints
7
Gynaecological, andrological and urinogenital
7
Respiratory
6
Parasites
6
Cardio-circulatory
4
Wounds
3
Typhus
2
Pain and inflammations
2
Teeth and gums
2
Incontinence
2
Bites
2
Headaches
2
Eye problems
2
Diabetes
1
Hernia
1
Otitis
1
Anemia
1
Medicinal treatments were most commonly prepared by boiling the plant part containing the active substance (34.5%), by crushing the dried part of the plant (23.6%), or by pounding the fresh plant parts, (21.8%), whereas sometimes the collected plant organs were used raw (18%) (Fig. 5b). These results are in accordance with investigantions carried out in the same region [5] and in general with other ethnobotanical studies in Tanzania, in which boiling to make decotions and pounding/grinding resulted to be the most common medicine preparation methods [13, 18]. Medical treatments were assumed by ingestion (77.4%), by dermal application (20.8%) and by inhalation (1.9%). Considering also the unclassified species (Additional file 2), other ritual methods can be found, such as the dispersion on the ground of the drug.
It should be taken into account that many of the traditional healing methods are based on rituals, dreams and spirit evocations (typical of every local healer), which most of the times are believed to be more important than the actual effect of plant medicinal remedies. This further diversifies the picture of traditional medicine, which largely varies from tribe to tribe, according to their own tradition.
Food and other plant uses
In total 53 plants were also indicated for food use: 21 were species collected in the wild, 30 were cultivated and 2 were both cultivated or grow spontaneously in the wild. Most of these belong to the Fabaceae family (6 species), followed by Solanaceae, Asteraceae and Cucurbitaceae (3 species each). The parts of the plants mostly consumed as food were fruits and seeds (55.6%), leaves (31.5%), roots (7.4%) and shoots (5.6%). Wild food plants do not play a key role in the diet of these communities and are not commonly used as famine foods. According to the present data, wild fruits such as Landolphia kirkii Dyer or Vitex doniana Sweet fruits, are collected as snacks by people working in the fields; wild vegetables such as Bidens pilosa L., Lactuca inermis Forssk. or Asparagus flagellaris (Kunth) Baker are used as side dishes; other species like Piper capense L.f. are added as flavours to some main dishes.
In general, fruits were eaten raw, while vegetables were consumed cooked in 80% of cases, while the remaining 20% was consumed raw or used for infusion to extract the aromas, such as Cymbopogon citratus (DC.) Stapf. Among species commonly collected in the wild there were Bidens pilosa, an herb used as a vegetable, and the fruits of Landolphia kirkii Dyer (Fig. 6b). Instead, Telfairia pedata (Sm.) Hook., a native cultivated species for collecting seeds (in order to extract oil), was indicated as progressively disappearing due to its low productivity compared to the new species of oil plant recently introduced.
Twenty-eight (19.4%) species were indicated as useful to produce raw materials (Fig. 4), of which 21 were woody species used for the production of furniture, house structural elements, firewood and poles. The other seven species were herbs (e.g., Poaceae and Cyperaceae) and palms which are mainly used for the production of fibers and roof covers (Fig. 6c). One of the most exploited species is Dalbergia melanoxylon Guill. & Perr. used because of its dark wood to make carved objects, such as figurines and necklaces. Phoenix reclinata Jacq. and Musa x paradisiaca L. were mainly used for the production of cordage and for weaving works as reported in Shangali et al. [19]
In addition, five other species (Fig. 4) were indicated as having ritual purposes linked to their traditional use within the communities. These species were thought to avoid bad luck (e.g., by drinking an infusion of Duranta erecta L. leaves and roots for 21 days, Fig. 6d), or against bad sprits or evil eye (e.g., bark of Ficus sycomorus L.). As also reported in [19], 2 plants were used to extract dyes (Bridelia micrantha (Hochst.) Baill. and Diospyros loureiroana G.Don). In the house gardens many species were just used as decoration, among which the most frequently cited by respondents were Dracaena fragrans, (L.) Ker Gawl. Bougainvillea spectabilis Willd. and Duranta erecta L. One wild tree (Brachystegia sp.) was indicated as pollen producer for bees, while the leaves of the wild poisonous tree Anthocleista grandiflora Gilg were used by local fishermens to stun fishes as also reported also by Shangali et al. [19]. Even in these rural community, as well as worldwide, Nicotiana tabacum L. leaves were used for the production of cigars. Finally, Capsicum chinense Jacq., Ocimum tenuiflorum L. and Bougainvillea spectabilis were indicated to be good repellent for insects (Fig. 4).
Conclusions
The present study revealed that numerous plant species are still essential in the everyday life of the tribes living in Kilombero Valley. These plants are commonly used for medicinal, food, weaving and building purposes. Most of the plants mentioned by the interviewed people were usually harvested in the wild, threatening the existence of some useful species. After the creation of the Udzungwa Mountains National Park, the collection areas were highly reduced concentrating the harvesting pressure on the few remaining areas of unprotected forest. Only few healers started to cultivate species for disease treatment, while almost all started to collect the plants in the neighbouring natural environment. Present data point out that half of the medicinal remedies were prepared from leaves (50%), while 16.7% were obtained from bark, 13.3% from roots, and 10% from the whole herbaceous plant. Harvesting practices like root excavation and stem decortication are causing a progressive depletion of many medicinal plant species. In addition, deforestation makes medicinal species harvesting areas increasingly scarce, forcing many local healers to abandon the practice. In the light of these facts, it is essential, in the immediate future, to educate traditional healers as well as common people to the sustainable use of the surrounding natural heritage. It seems also necessary to provide the populations with additional means to increase the forested areas, such as the distribution of seedlings for biomass production. Although some efforts have already been made in the studied territory, and in spite of a firm tradition in Tanzania of community-based forest conservation, the situation remains critical and the state of unprotected forests near these villages is deteriorating year after year. This situation, if not quickly reversed, may lead to an unprecedented environmental crisis and to the loss of much of the traditional ethnobotanical culture. In this context, the present study wishes to contribute, at least to some exent, to preserving the knowledge present in the investigated populations, still deeply connected to nature, and to passing down this unevaluable tradition to future generations.
Acknowledgements
We wish to thank the Udzungwa Ecological Monitoring Centre (P.O. Box 99, Mang’ula - Tanzania) staff for their logistical help, Dr. Silvia Ricci and Dr. Francesco Rovero of the Mazingira Association (Trento, Italy) for the precious help provided in searching and contacting candidates for the interviews and Dr. Henry J. Ndangalasi (Dept. of Botany, Dar-es-Salaam Univerisity) for the collection of herbarium specimens. We also wish to thank Mr. Nicodemo Mele (University of Bologna) for helping in editing colour pictures and Dr. Marianne Louise van Buuren for edinting the English language.
Funding
Not applicable.
Availability of data and materials
All data generated or analysed during this study are included in this published article (and its Additional files).
Authors’ contributions
MS and RV conducted field work and drafted the manuscript. RV and CB designed the study. AT contributed to the preparation and critical revision of the manuscript. All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
Not applicable.
Ethics approval and consent to participate
Not applicable.
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