Taxonomic diversity of medicinal plants

A total of 170 medicinal plants were identified from the study area, which belong to 144 genera and 65 families. Fabaceae and Asteraceae were the most dominant medicinal plant families represented by 20 and 18 species, respectively, followed by Euphorbiaceae and Solanaceae (eight species each), Cucurbitaceae (seven species), Lamiaceae (six species), Apocynaceae and Vitaceae (five species each), Apiaceae, Malvaceae, Poaceae, and Rubiaceae (four species each), Acanthaceae, Asparagaceae, Moraceae, Polygonaceae, Ranunculaceae, and Rutaceae (three species each), and the remaining 47 families were represented by two or less medicinal plant species each (Table 2). Genus Solanum was represented by four species, followed by Cyphostemma, Echinops, Euphorbia, Ficus, and Rumex genera, represented by three species each, and the other remaining genera had two or one medicinal plant species each.

Table 2 The number of medicinal plant species and genera in each family

Consistent with the current study, other studies conducted by [30, 34, 35] in different parts of Ethiopia reported the dominance of medicinal plants within the Fabaceae and Asteraceae plant families. This might be because of the phytochemicals shared among medicinal plants in the same taxonomic categories [36]. Hence, medicinal plants in the Fabaceae and Asteraceae families could be rich in bioactive chemical compounds that contribute to their therapeutic roles. In contrast, some researchers [37, 38] justified the point of view that Fabaceae and Asteraceae are the most widely abundant families in the Flora regions of Ethiopia than other plant families.

Growth habit of the medicinal plants

The most dominant growth habits of medicinal plants in the study area were herbs (61 species, 35.88%), followed by shrubs (39 species, 22.94%), trees (38 species, 22.35%), and climbers (22 species, 12.94%), while subshrub growth forms were found to be the least (10 species, 5.88%) (Fig. 2). In agreement with the current study, previous studies [34, 37, 39,40,41,42] conducted in different areas of Ethiopia reported the dominance of herbaceous medicinal plants. This might be due to the more widespread distribution of herbaceous plants than plants of other growth habits [35, 41]. However, other studies in Suro Barguda district, southern Ethiopia [38], and in Kebridehar and Shekosh districts, southeast Ethiopia [43] revealed the dominance of shrub growth forms of medicinal plants. In this sense, the habits of medicinal plants in these areas might be different from the current study area due to the dominance of shrubby vegetation types and their geographic locations in semiarid or arid areas of the country.

Fig. 2

Growth forms of medicinal plants in the Dibatie district

Cultivation status of medicinal plants in the study area

Results showed that most (135 species, 79.41%) medicinal plants in the current study area were harvested from wild habitats. While some (32 species, 18.82%) medicinal plants were found as cultivated plants, a few others (three species, 1.76%) were found to be semi-wild (Fig. 3). This indicates that the cultivation of medicinal plants in the present study area is very low. Similarly, previous studies elsewhere in Ethiopia [9, 15, 30, 35, 37, 44, 45] reported that medicinal plants are usually harvested from wild sources and rarely available as cultivated plants or as both cultivated and wild plants. The abundance of medicinal plants in the wild habitat increases their exposure to different threats like overexploitation [15, 46], deforestation, and habitat destruction [47]. Thus, the practice of domesticating medicinal plants is important to access the plants easily and to ensure their survival in the future.

Fig. 3

Cultivation status of medicinal plants in the Dibatie district

Proportion of medicinal plants used to treat human and livestock ailments

Out of the recorded medicinal plants, 105 species (61.76%) were used to treat only human ailments, 13 species (7.65%) were used to treat only livestock illnesses, and 52 species (30.59%) were used to treat both human and livestock ailments (Fig. 4). The documented medicinal plants were traditionally used for the treatment of 79 types of human ailments and 29 kinds of livestock ailments. The most commonly treated human ailments were snake venom, wounds, diarrhea, general malaise, impotency, toothache, tonsillitis, boils, evil eye, hemorrhoids, placenta retention, rabies, abdominal pain, hepatitis, lymphadenitis, rectal prolapse, swelling, leishmaniasis, ascaris, cough, choking, gastritis, Bell's palsy, gonorrhea, arthritis, scorpion venom, eye disease, tapeworm, tinea versicolor, and vomiting consecutively, among others based on informant citation. While the commonly cured livestock ailments were found to be blackleg, rabies, wound worms, diarrhea, placenta retention, breast swelling, eye disease, hemorrhoids, snake venom, Newcastle disease, tick infestation, constipation, denying of milk, milk deficiency, swelling, wounds, ascaris, cattle thinness, colic, choking, difficulty of excretion, febrile disease, chicken lice, leech infestation, lumpy skin, mouth wound, respiratory disorder, sneezing, and difficulty of urine flow successively (Additional file 1).

Fig. 4

Proportions of medicinal plants used to treat human or livestock diseases

The number of human ailments traditionally treated by the medicinal plants in the present study area was comparable to the number of human ailments (81) reported in Asagirt district, northeastern Ethiopia [34]. The number of human ailments stated to be treated in the present study was greater than those of earlier studies [17, 37, 39, 42, 45, 48,49,50] in different regions of Ethiopia. On the other hand, the number of livestock ailments reported to be treated by the medicinal plants in the current study exceeds those of previous findings [9, 14, 15, 17, 39, 45, 49], but is exceeded by the study [51] conducted in the Adea Berga district of West Shewa zone, central Ethiopia. The current results showed that multiple ailments could be treated by a single plant species, and more than one plant species could also be used to treat a single ailment, in line with the previous reports [17, 34] in Ethiopia. The results clearly indicate the rich medicinal plant diversity and strong relationships between the plants and residents in the current study area with respect to human and livestock health care. This might be because of the predominance of mixed agriculture (crop cultivation and animal husbandry) and the remoteness of the area for access to modern health care.

Medicinal parts of the plants in the study area

In the study area, most (70 species, 41.17%) medicinal plants provide multiple medicinal parts from a single plant, followed by medicinal plants with leaves (29 species, 17.06%), roots (19 species, 11.18%), bark (14 species, 8.24%), tubers (11 species, 6.47%), seeds (eight species, 4.71%), and whole plants (eight species, 4.71%) as the common remedy parts. The others contribute medicinal parts such as fruits (four species, 2.35%), exudate (three species, 1.76%), aerial parts (two species, 1.18%), and stems (two species, 1.18%) (Fig. 5).

Fig. 5

Remedy parts of medicinal plants in the Dibatie district

The current results showed that multiple plant parts were prepared as remedies from a single species, consistent with studies in other countries [52, 53] and less frequently in Ethiopia [30, 37, 54]. This indicates the pharmaceutical potential of the plants due to the presence of bioactive phytocompounds in many parts. Besides, the present study revealed most (29 species) medicinal plants with leaves as remedy parts next to plants with more than one remedy part (70 species). Similarly, leaves were reported as the most commonly used medicinal plant parts in different regions of Ethiopia [34, 37, 39, 44, 46, 55] and other countries [52, 53, 56]. The regular use of leaves as traditional medicine might be due to the ease of preparations and the excess of bioactive compounds that promote their efficacy [42, 52]. The use of leaves instead of other plant parts can minimize risks related to the loss of medicinal plants [44]. Nevertheless, frequent utilization of whole plants [57,58,59] and roots [43, 60,61,62,63] has been reported in different parts of the world, including in Ethiopia. However, extensive use of whole plants and roots of medicinal plants can pose adverse effects on their survival and continuity in the future [52, 64, 65] though the use of rhizomes, bulbs, flowers, bark, and stems may also cause destructive effects relative to the harvesting of leaves [42, 66, 67].

Use conditions of the medicinal plants

The medicinal plant parts in the present study were mostly used in fresh form (60.13%), followed by either fresh or dry condition (31.28%), and sometimes utilized in dry state (8.59%) (Fig. 6). Likewise, several researchers [34, 37, 41, 42, 44,45,46] reported the fresh preparation of traditional medicinal plants elsewhere in the country. A fresh prescription was often performed to give a remedy immediately to the patient. Utilization of fresh medicinal plants may have the advantage of reducing the loss of bioactive phytochemicals upon drying, thus enhancing their efficacy [39]. However, the frequent use of fresh remedies has been considered one of the threats to medicinal plants since they are not preserved for later usage [38]. The current finding also verified that some medicinal plants were prescribed in dry conditions and could be stored for months or a year with efficacy in healing. This might be due to the fact that dry remedy preparation increases the shelf life of the medicine [42].

Fig. 6

The use conditions of medicinal plant parts in the Dibatie district

Preparation methods of the medicinal plants

Results showed that local communities prepare herbal remedies mostly by crushing (25.49%), followed by pounding (19.12%), chewing (11.11%), powdering (8.50%), squeezing (8.17%), heating (6.54%), boiling (4.58%), rubbing (4.41%), exuding (3.92%), cutting/slicing (2.61%), burning (2.12%), roasting (1.63%), and sousing (0.98%), and there was also direct consumption (0.82%) of some medicinal plant parts without processing (Fig. 7). The present findings agreed with numerous ethnobotanical studies [11, 30, 34, 37, 41, 43,44,45, 50, 68], which reported crushing medicinal plants as a common means of traditional remedy preparation in many areas of the country. However, other studies reported grinding [49], pounding [38, 42, 46], and squeezing [