General data

The elderly informants were the main reference for traditional knowledge, and the young showed a weak of information. Local people in southern Yemen use traditionally wild plants as natural sources for medicines and food, as well as for a variety of other purposes. This study reports the ethnobotanical data of wild plants from southern Yemen concerning traditional domestically and other non-medicinal non-food uses of plants.

The survey identified 73 wild plant species belonging to 28 family with various local traditional uses (Table 2). The most dominant wild plants belong to Fabaceae (14 species) mostly Acacia species, which are of particular importance as constructions materials and as forage for livestock and beekeeping. This is followed by Asteraceae (6 species), Malvaceae (5), Apocynaceae (4) and Moraceae (4) (Table 2). Most used plants are trees (27 species) followed by shrubs (24 species), herb (19), and grass (2) and one plant as a climber. While the most common useful parts of plants were reported as stem (37 species), leaf (30 species), wood (27), flower (12), entire plant (16), fruit (8), bark (7), gum (2), latex (2) and liquid exudate (1). Various wild plant species have high abundance in the flora of the plant study areas, showed importance for the environment and people. The number of wild plants in southern Yemen studied is more than the number of wild plants used as edible food plants [8] but much less than those used in traditional medicines [7].

Distribution of the plant species

Ocimum forsskalii is endemic to southern Yemen. Two reported plants are endemic to southern Yemen and west of Oman: Cynanchum vanlessenii, and Vachellia yemenensis. Ziziphus leucodermis and Boscia arabica. Species endemic to Arabian peninsula are Aloe sabaea and Dracaena serrulata. while Euphorbia cactus is endemic to Arabian Peninsula and islands of Kanari. Many species were determined to have distribution only in the regions of Arabian Peninsula, and African Horne, these include: Cyphostemma digitatum, Euryops arabicus, Grewia tembensis, Grewia trichocarpa, Indigofera arabica, Kleinia odora, Searsia retinorrhoea and Senegalia asak [7].

IUCN STATUS of the threatened plants

From reported plants, some species have been enlisted in the IUCN (conservation status) Red List of Threatened Species. According to IUCN STATUS, Dracaena serrulata was enlisted as (EN) endangered species and Boscia arabica has been classified in VU (Vulnerable) group. Twelve species have been assessed in less threatened group described as Least Concern (LC), these include Ficus cordata, Ficus palmata, Ficus vasta, Grewia tenax, Hyphaene thebaica, Lycium shawii, Salvadora persica, Senegalia mellifera, Tamarix nilotica, Tarchonanthus camphoratus, Vachellia seyal and Ziziphus spina-christi. Despite the widespread spread of these plants within the country, they face many dangers, the most important of which is excessive, irrational consumption, in addition to urban sprawl in rural areas, which threatens large areas of these plants, in addition to the lack or absence of rain in the southern regions of Yemen.

Categories of traditional uses

These 29 local wild plant species were classified into nine main classes according to the local traditional domestic uses (Table 3). The most cited five categories were construction timber (18 species with 788 citations), handicraft (26 species with 739 citations), economic plant products (17 species with 694 citations), agriculture tools (24 species with 648 citations) and beekeeping (15 species 571 citations) (Table 3). This study showed that the traditional knowledge in southern Yemen is rich and has broad purposes in directions other than the traditional uses of wild plants in medicine and food. The three categories with highest number of plants species were handicraft (29 species), agriculture tools (24 species) and animal husbandry (21 species).

Table 3 Categories of traditional general uses of wild plants in order to high citation numberWild plants used as source for traditional domestic handicraft work

The first category is the wild plants that are used as natural sources for traditional domestic handicrafts (29 species with 739 citations); this includes fibers tools: rope, cordage, basket, mat, hat, pillows, broom, (14 species), cook and kitchen tools (12 species), broom and defense tools (4 species) (Tables 2, 3).

Fibers

Dracaena hanningtonii (syn. Sansevieria ehrenbergii) (seni) is the most common local wild plant that used traditionally for obtaining fiber for making traditional handicraft of rope "habl" and cordage "habl", and slings thin cord "walaf" (Fig. 2). The process of making fiber is called locally (sehieg); where the leaves are loosened by hit or rubbing with a sharp stone to remove the epidermis of leaf and to get the fibers and wrapped twisted on the thigh for weaving and making thin ropes (sehieg) that is sling-like. Th sling is the famous traditional product obtained from the fibers of the leaves of D. hanningtonii to protect crops from birds; it is named locally “walaf, wadhaf” (Fig. 2). This sling is used by local people for throwing small stones to expel birds away from the agriculture field protect their crops, especially wheat, from attack of these birds. Such traditional slings are known as weapon in indigenous traditional knowledge in South American [33]. We observed that there is no difference between the forms of both slings made by local people in southern Yemen and by Native Americans. D. hanningtonii is used as a source of natural fibers and traditional rope making in other tropical regions such as Tanzania and Ethiopia [18, 34, 35]. Its leaves fiber contained cellulose, hemicellulose and lignin; this natural cellulose showed a tensile strength of 50–585 MPa [36].

Fig. 2

a Wild plant as a natural source for fibers used traditionally in southern Yemen, its scientific name Dracaena hanningtonii (Sansevieria ehrenbergii); it is locally called "seni". b Traditional sling named locally "walaf or wadhaf"; it is prepared traditionally from fibers of leaves  of Dracaena hanningtonii. The photos were taken by the author

In addition, the leaves of Dracaena forskaliana (Sansevieria forskaliana) are used as fiber source in case of lack of D. hanningtonii (S. ehrenbergii). In addition, barks of some plants can be used as fiber sources for making cordage and ropes such as inner barks of Ficus cordata and Ficus vasta, while less use was reported for bark of Calotropis procera and Hyparrhenia hirta. Other fibers can be used to make baskets, rope and cord from the leaves of Dracaena serrulata and Hyphaene thebaica and Typha domingensis. Dracaena serrulata was reported in Oman for rope making [17].

On the other hand, the cultivated palm tree Phoenix dactylifera L. (Arecaceae) (nakhil) is considered one of the most important cultivated plants used locally for various purposes, including the use of its leaves (azaf) in the manufacture of mat (haseerh), basket (sellah), hand fans (marwaha), hat (qubaah), ropes (single: "habl"; plural" hibal) and bed stead (qaadah) (Fig. 3). The date palm is the most used tree in Arabian Peninsula countries to make these traditional tools such in Oman [17]. Generally, the date palm tree has been famous in the countries of the Arab world since the dawn of history as a source of food and medicine (fruits), handicrafts used both domestically and abroad (leaf fibers) and construction (wood).

Fig. 3

Handicraft made from the plant fibers. a Dining mat, b hand fan, c, d pot for storing bread. The photo was taken by the author

Pillow filling

The fruits (diaspores) of Aerva lanata and Aerva javanica are usually used for making pad for sleep and for filling pillows and saddle of donkey in study origins. The same use of A. javanica as a natural material in pillow stuffing is also found in Pakistan and Oman [17, 37]. Fruits of Tarchonanthus camphoratus used for Pillow filling but with less citation.

The results showed that there are three types of fibers documented in the study according to the used parts: leaf fibers, bark fibers and fruits (diaspores) fibers. It is said that the leaf fibers of Dracaena hanningtonii are the hardest fibers. In addition to wild sources of fibers, the fruits of Gossypium hirstum are cultivated in Zingibar (Abyan) that gives most important cotton fibers in the last seven decades.

Cook and kitchen tools

Woods of Vachellia nilotica (Acacia nilotica), Vachellia etbaica (Acacia etbaica), Vachellia seyal (Acacia seyal), Senegalia hamulosa (Acacia hamulosa), Commiphora gileadensis and Tamarix nilotica are locally used to make wooden cup, wooden plate and wooden pestle for crushing vegetables such as onions and garlic.

Stems of Vachellia gerrardii (Acacia gerrardii), Senegalia asak (Acacia asak), Cordia quercifolia, Olea europaea subsp. cuspidata and Grewia tembensis were reported to use as solid long sticks after removing the outer barks of the stems. This prepared stick is used by hand as manual wooden mixer (medhrar; mahwasch), to mix flour Mel (taheen) with boiling water during cooking. The common food made by this method is called locally (zad); this traditional food is served in a special wooden bowl (kuaadah) with hardness character and a smooth surface which made of wood from Ziziphus spina-christi or Vachellia nilotica. It is said that many people in the countryside still prefer to eat the specific meal (zad) in this wooden bowl because it gives a.

House cleaning tools (broom)

The whole herb of Pulicaria undulata and Euryops arabicus and the leaves of Schoenoxiphium sparteum, and Hyphaene thebaica were reported to use as traditional brooms for house cleaning. Dried herb P. undulata of is an aromatic plant therefore, after cleaning; it spreads aromatic smell in the house.

In Europe, other plants are used to make traditional brooms. Among these are plants of the genus Artemisia, which gives an aromatic scent after sweeping [38], while plants of the genus Pulcaria are used in southern Yemen.

Commercially, these traditional brooms are made from the palm tree, especially in Hadhramaut and Lahj. The manufacture of traditional brooms from local plants helps many poor people, especially women, as a source of income for the family, as is the case in other world regions such in south Africa [39].

Defense tools

In the past, the local people in some study areas have used the ashes of sticks of Calotropis procera to mix with sulfur and salt to make “gunpowder-like”. The bark of Ficus cordata is used to make a wick for setting fire to ancient guns. Stick from Cordia quercifolia is used as defense tool called (assa, mohwer). Buxus sempervirens was the first plant from which humans made pointed sticks for protection or for lighting fires. It was a 171,000 years ago in the late Pleistocene era, when wooden tools were found at an archaeological site in Italy [40].

The manufacture of handicrafts from plants is similar to neighboring Arab countries, such as Oman, where handicrafts are widespread among rural people, mostly in both countries, and they are distinguished by high skills. They are still widespread in Yemen, but in Oman and the Gulf countries, the handicraft profession declining due to dependence on the petroleum industries [20].

Wild plant used for making agriculture tools

The second category is plant used for making agriculture tools with 24 species with 648 citations. This category is classified into tools for plowing: wooden plow (mehrath) (11 species), harvesting tools (8), wooden grain measure (4), handle of axe (fas) (1), poles (3) and fence (3) (Tables 2, 3).

In southern Yemen, agriculture often depends on torrents of rain. It also relies on traditional wells that were dug by ancestors with traditional tools, but in the past three years, the construction of dams in the valleys and the digging of tubewells has introduced. Changes in climate and the increase in temperature have led to a decrease in the level of rainfall in southern Yemen, which rarely falls, especially in the southern regions, and devastating floods often occur. This scarcity of rain has led to water scarcity and thus a lack of agriculture and livestock production, and water no longer reaches the population in cities on a regular basis. Such arid tropical climatic conditions affecting agriculture also exist in neighboring countries [41].

The development of traditional agricultural tools and thus agricultural methods among the Yemenis since the beginning of the history of agriculture in Yemen led to the purification and selection of crop varieties that doubled during the pre-Islamic and medieval eras such as the number of wheat and sorghum verities [42].

In the countries of the Arabian Peninsula, which are rich in petroleum resources, the craftsmanship of handicrafts has declined greatly due to the exploitation of oil resources in industry and due to the increasing import of goods [43]. Conversely, in Yemen, which is still in economic weakness, these crafts are still continuing among the people of the countryside to cover the internal needs of popular handicrafts.

However, most population of Yemen are living in the rural areas and are poor. Therefore, there is a continuing increase in the dependence of poor people on natural rural resources of livestock, fuel wood, crops and fodders.

The traditional plow (mehrath)

The traditional agriculture knowledge in southern Yemen has ancient history including traditional soil tillage system. The traditional wooden plow (traditional plough) (mehrath) is pulled by two oxen (dhamed). Its components are the share (sehb) made up of steel and the main handle made up of Acacia wood. The handle and the beam, which connected to a wooden yoke, hanged on the necks of two oxen (dhamed) that pull the plow during tillage of the soil. The handle is made from woods of Acacia species including Vachellia nilotica, Senegalia hamulosa, Senegalia mellifera and Senegalia asak. In addition, wooden plow (mehrath) is made from wood of other preferred species such as Ziziphus spina-christi, Balanites aegyptiaca, Commiphora kataf, Cordia quercifolia, Ficus sycomorus, Ficus cordata. The yoke (heig) is made up of woods Commiphora gileadensis, C. kataf and Cordia quercifolia. It is said that these used woods make plowing easy and facilitate the tillage process, because they are light and durable woods. The stem of Calotropis procera was reported to use as hollowing stick as wooden tube (medhrah) connected to the wooden plow (mehrath) to pour and distribute the seeds during tillage. The traditional plowing (mehrath) aids for conservation of agriculture in southern Yemen since the ancient times. The inherited traditions of using natural sources remain the safest in the face of mechanical industrial intervention affecting the environment, such as the traditional use of agriculture [44].

The ancient agricultural terms and farming techniques in Yemen since pre-Islamic history that were revealed in the archaeological inscriptions have not changed much in the local language until today [16]. Likewise, post-Islamic agricultural reforms found in the medieval Arabic manuscripts are still used by the population in the rural origins in Yemen, for example the Arabic local name for plough " mihrath" or "mehrath" and described the Yemeni usage of plowed furrow [45].

Harvesting tools

The handle of sickle (masrab) is made up of wood Vachellia nilotica for harvesting process for crops, cereals and grasses. To separate the grains from the ears of the corns, a solid stick from the stems of wild plants can be used as a beater (stick). This wooden grain separator is locally called (malbag or moher). The bark is removed from stem that used as stick (moher). It is made up of wood from selected plants including Grewia tenax, Grewia tembensis, Grewia trichocarpa, Senegalia asak, Vachellia yemenensis, Lycium shawii or Ehretia cymosa. The farmers use the wooden separator to separate the grains by beating the ears of the cereal harvested crop. Similar uses for other species of Ehretia (E. btusifolia) was reported was found to use for making same agriculture tools in Pakistan [19]. To remove impurities from grains of crops, the herb of Pulicaria undulata is used for sweeping these unwanted materials from grains.

Wooden measuring tool

A wooden bowl is locally called (mekyal); it is a wooden grain measure that is used as volume unit of measure for grains of cereals, coffee fruit, and sesame seeds. It and made up of the wood of Commiphora kataf, Commiphora gileadensis and Ficus sycomorus. Wood is hard yet light. This facilitates the process of filling the bowl and pouring its content during the process of weighing.

Wooden ax (fas) and shovel (magrafah)

The handle of the wooden ax (fas) is made up of stem of Grewia tenax and Searsia retinorrhoea. Stem of Grewia tembensis can be used to make wooden handle of hoe (magrafah), which is used to dig the soil manually. In Sudan, G. tenax wood was reported as common source for making agricultural tools [46]. Documenting agricultural methods and their development, such as the plow, sickle and axe, in ancient societies facilitates knowledge of the dynamics of agricultural development in the society [47].

Trees as Fencing for field

The trees of Ziziphus spina-christi are planted as hedge for protect agriculture fields. The view of the farms and fields in the countryside of southern Yemen is familiar with an ocean of zissovo trees, which carry the crops from the wind and provide suitable shade for them and for the farmers and shepherds. Stems of Ficus cordata are used to make fences to protect the coffee, corn and millet plants.

Tamarix nilotica works to repel wind and sand. In southern Yemen, other cultivated and introduced plants were planted to protect against the wind and also to improve the tropical climate since thirty years ago, these include introduced plants Conocarpus lancifolius in Aden [48]. Parkinsonia aculeata, Prosopis juliflora, Prosopis farcta and Prosopis cineraria between Aden and Hadhramout,

Wood aiding in drawing water from the well

Stems of Ziziphus spina-christi, Vachellia nilotica and Vachellia etbaica were reported to use for building wooden poles on the well to draw water in a bucket.

Wild plant used as health care aids

This third category deals with 21 plants species with 570 citations; it contains some subcategories including insect repellant (7 species), preservative agent (6 species), cleansing (5), shade tree (3) and walking stick (2) (Tables 2, 3). The traditional uses of many wild plants were reported in the field of general health care of human and animal.

Insect repellant and fumigant

The dried stem of Cynanchum viminale subsp. stipitaceum (Sarcostemma viminale subsp. stipitaceum) is burned as fumigant to use as incense (fumigant); it is said it makes healthy air after childbirth and used also for cloths of new births. In addition, the dried leaves of Aloe inermis and Aloe vacillans are used as fumigant to repellant insect during childbirth. On the other hand, Aloe trichosantha is traditionally used in Ethiopia to repel insects [49].

Seven plants were reported to repellant insects including Aloe inermis, Aloe vacillans, Artemisia abyssinica, Blepharis ciliaris, Cynanchum vanlessenii and Cynanchum viminale. The squeezed liquid of the fresh leaves of Blepharis ciliaris is sprayed at home to kill fleas. Stems of Cynanchum vanlessenii and Cynanchum viminale were burned as fumigant to repellant the insects in livestock housing. The herb of Artemisia abyssinica was placed between the clothes to repel insects. In addition, the essential oil from Artemisia absinthium has been proven to be insect repellant [50].

Preservative agents

The powder of the leaves of Vachellia nilotica (Acacia nilotica) is traditionally added in small amount in drink water container as preservative agents (qaral). This local traditional use has been confirmed in our previous study that identified its strong antimicrobial and antioxidant activities [51]. Woods of some plants can be used as container for drink water for livestock such as wood of Vachellia etbaica (Acacia etbaica) and Ficus cordata, Commiphora gileadensis where a rectangular cavity is made in the stem of the plant to store water. It is said that these stems preventing the attacks of insect and the microbial contamination. Fresh raw herb of Indigofera arabica is rubbed on the wooden pots, followed by burning part of the herb; it is said that its fumigant has activity against microbial contamination therefor it used as preservative for drink water or food. Fresh herb of Artemisia abyssinica is cut in small pieces, and it is distributed in rooms and between document papers, to preserve against insect attack. The fumigant of the dried juice of Kleinia odora is used as incense after childbirth against attack the microbes. In Ethiopia, this plant is traditionally used to expel insects [49].

Cleansing agents

Wild plants are used as hygienic agents for human hair and body care. Some cited plant species are used as natural soap and shampoo, for washing body and hair including leaves of Corchorus depressus, Corchorus trilocularis and Ziziphus spina-christi powdered and mixed in water. This mixture is used to smear women hair for some hours and followed by washing to clean. Ziziphus spina-christi is the most common plant used to wash hair by women as traditional shampoo. The leaves powder of Z. spina-christi is mixed in water; this is called “qasel”; its powdered barks are mixed in little water as paste; this is called "lagub".

Both preparations are used as shampoo to wash and clean women hair. In addition, paste of leaves of Tarchonanthus camphoratus was reported to clean body as soap.

Shade tree

In southern Yemen, the sub-tropical climate is dominant during the year [1]. Therefore, the shade of trees is an important factor to protect people and livestock from the hot sun. Two plant species widely have high abundance in each study areas and are used for shade to protect humans and livestock from the sun in the tropic areas: Ziziphus spina-christi and Vachellia tortilis. In addition, Vachellia tortilis grows in the arid areas during years without rain; therefore, it is the most important tree as housing and shade for livestock because of its strength and steadfastness to protect against the sun and wind (Fig. 4).

Fig. 4

a, b Vachellia tortilis (Acacia tortilis) is an important plant used traditionally in southern Yemen as source for bee forages, b flowers of Vachellia tortilis c bee hives d dead stems of Vachellia tortilis used as good firewood and for prepared charcoal. The photos were taken by the author

Walking sticks

Stems of Grewia tenax and Grewia tembensis were reported to make good and strong walking stick to help elderlies or sick persons to walk.

Flavoring agent

Senegalia mellifera barks are burn and used as fumigant into pot to get good taste and smell by storing food.

Wild plants used as source for products with economic value

The fourth category is the economic and commercial plant products from 17 species with 694 citations. These natural products are classified as dyestuff (5), charcoal (5 species), ink (3), tanning agent (4), flavoring agent (4), Arabic gum (2), refreshing drink (1) and fixed oil (1) (Tables 2, 3). Natural products from plants have economic value that helps improve the family's income such as gum, dyes and charcoal. On the other hand, the study shows promising sources of natural materials that can be used in general industries, such as pen ink and tanning materials.

Dyeing

Some common wild plant species are used traditionally as dyestuffs. Indigastrum costatum (black color) and Indigofera tinctoria (dark blue color) for dyeing of hair or body of women or men. Powder of the dried leaves of each plant are mixed in water as semi-solid, smear on hair and let drying in air or under sunlight.

The leaves of Indigofera tinctoria (blue to black) and Indigofera coerulea (black) are mixed together in boiling water to make dark blue dye solution for cloths. The leaves powder of both Indigofera tinctoria and the cultivated Lawsonia inermis is used as mixture to make red dye paste for hair and clothes. The responsible natural compound for the blue color of Indigofera tinctoria is indigotin [52]. Indigofera species such as I. tinctoria are well known to use as traditional dyeing in old world including south Europe [53].

Dyeing is one of the traditional uses of local plants that have declined and are nearly extinct. It must be revived through blogging and educating young people in workshops. Hadhramaut is the main geographical origin of henna in Yemen where there are also many ways to use it as a coloring material for hair, hands and feet [11]. The henna trade is one of the most important commercial agricultural activities in Hadhramout Governorate.

Charcoal

Vachellia tortilis wood was reported as high cited to provide the good charcoal from Abyan and Shabwa in the study area, which is exported to other southern Yemeni areas. Alternative plant wood-making charcoal was reported for Vachellia etbaica. Vachellia tortilis is reported in other countries as the most selected Acacia species for charcoal production, such as Ethiopia and Oman [54, 55].

Natural ink

The juices (saps) of Aloe vacillans and Aloe inermis are mixed with the black smoke obtained from burning wood. This mixture is used as pen ink for writing that is not erasable.

Tanning agent

The dried leaves of Vachellia nilotica (Acacia nilotica) were high cited (100%) to use for tanning animal leather that use by local peoples in the study area until today (Table 2). Alternative wild plants were cited to use as tanning agents include leaves of Vachellia gerrardii and Cyphostemma digitatum. In addition, leaves and latex of Calotropis procera were cited to remove the hair of animal skin before leather tanning, mostly in Hadhramout.

Generally, the leaves of V. nilotica (Acacia nilotica) are known as rich natural source of tannins used for tanning leather [56]. In some Arabic countries including Oman and Sudan, the legume fruits of Vachellia nilotica (Acacia nilotica) are used as tanning agents; these tannins were reported to use in the manufacturing of the leather [17, 57, 58]. Barks of Acacia mearnsii and Acacia xanthophloea are traditionally used as tanning agents to make leather Tanzania [59]. Similar use for Calotropis procera was reported in the neighboring country Oman [17]. Recently, it was identified that the latex of the C. procera is safer and most suitable to the environment than the chemical agents to remove the hair of the leather [60].

Arabic gum

The most important Arabic gum is produced by incision of the stems of Senegalia hamulosa and Vachellia nilotica. Their dried liquid exudates form high valuable Arabic gum. Generally, the Arabic gum is well for its high value as pharmaceutical aid for drug forms such as tablet and suspension; moreover, it shows also antimicrobial activities [61]. As a result of nature's dependence in Yemen on rain only, the spread of acacia plants is small compared to Sudan, which is considered an important geographical origin for the trade in gum Arabic; therefore, the income from gum Arabic is high for the people who work in its production in Sudan [62], due to the importance of Gummi Arabica in the manufacture of various pharmaceutical forms such as tablets and suspensions.

Generally, Acacia species are considered an important source of income for families in rural areas in various tropical regions. They are a source of production of construction wood, gum, tannin, firewood and fodder for livestock [63].

Refreshing drink

The stem of Hyphaene thebaica produces liquid exudate by incision of the stem that is traditionally used as a refreshing, and relaxing drink with sour taste. This juice of stem was not biological investigated, while in the fruit many bioactive compounds were identified including saponins, coumarins, hydroxyl cinnamates, essential oils and flavonoids. In addition, the fruit of the plant contains sugars, protein, fats and minerals [64].

Fixed oils

From seeds of the wild plant Ziziphus spina-christi, the fixed oil is extracted. This fixed oil has become very popular nowadays and is sold by young people and children in the countryside. It is used for many medicinal and food purposes [7, 8]. On the other hand, sesame oil is used from the sesame plant (Sesamum indicum) widely grown in the countryside as a basic food and traditional medicine and for commercial purposes that help generate income for farmers.

Wild plants used as construction (timber) materials

T