Open Access

Traditional knowledge on wild and cultivated plants in the Kilombero Valley (Morogoro Region, Tanzania)

Journal of Ethnobiology and Ethnomedicine201713:17

https://doi.org/10.1186/s13002-017-0146-y

Received: 5 December 2016

Accepted: 17 February 2017

Published: 9 March 2017

Abstract

Background

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.

Keywords

Ethnobotany Ethnomedicine Medicinal plants Udzungwa Mountains National Park Kilombero Valley

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 [13]. 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].

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.

Previous ethnobotanical studies have been conducted in Tanzania with the main purpose to investigate ethnomedicinal knowledge of local healers [9, 12, 13, 1618], 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.

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. a Solanum 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

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].

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; d Duranta 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.

Declarations

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.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Biological, Geological and Environmental Sciences, University of Bologna
(2)
MUSE - Museo delle Scienze

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Copyright

© The Author(s). 2017

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