A total of 133 informants of different demographic groups were interviewed on the therapeutic properties of medicinal plants throughout the 22 villages under study (Table 1). As indicated in the table, informants were almost of equal shares of women and men. They constituted five age groups falling in the range of 19–97 years with the majority being 40–80 years. Informants were also of different educational backgrounds. Farmers and housewives together represent the majority of informants' professions, whereas other professions were exemplified by a few persons only.

Table 1 also shows the percentage of botanical data per informant group. While males provided 58% of the cited species, females presented the remaining number (42%). Older age groups cited more plants than younger age groups with most plants (89%) being cited by informants of the 40–80 years. Moreover, 71% of cited plants were provided by informants who had lower level of education (i.e., no schooling, primary, and intermediate levels). As for the profession aspect, farmers and housewives representing 85% of the total number of informants, provided 82% of the cited plants. Despite their small number (5 informants, 4%), traditional practitioners provided 13% of the cited plants.

The pattern of distribution of informants’ knowledge related to religious background shows that the majority of species (81%) were cited by Druze informants. Whereas, each of Sunni and Christians provided 13% and 6%, respectively, noting that all the cited species by the latter groups were common with the former one. Among these species were Salvia fruticose for colic and stomach/intestinal troubles, Matricaria aurea (Loefl.) Sch.Bip., Micromeria myrtifolia, and Myrtus communis, for cold and flu. Interestingly, some informants of the Druze religious group identified a few species such as Acantholimon libanoticum Boiss. and Laurus nobilis L. for their importance in spiritual protection against diseases and witchcraft. As for the main source of informant's knowledge, oral transmission of ancestors (71%) was reported as the main approach through which informants acquired their knowledge about the medicinal properties of plants and means to use them. But, self-training using traditional manuscripts, modern online means, and contemporary books represented 25% and learning from fellow herbalists and traditional practitioners formed 4% only.

The floristic analysis of cited species reveals a list of 184 plant species of medicinal properties used for the treatment of a wide range of diseases. Additional file 1: Table S1 (quantitative and qualitative ethnobotanical data of wild medicinal plants in the Shouf Biosphere Reserve, Lebanon) presents the scientific and common names, botanical families, and life forms of these species. It also presents plant parts used, therapeutic indications, preparations and administrations, dosages, along with quantitative analysis values (FC, RFC, UV, RI, and FL) used as a tool for the prioritization of certain species for future pharmacological research and development projects. Remarks provided by informants such as other uses, toxicity, and endemism are also included.

The cited species belonged to 57 families with Asteraceae (31 spp.) having the predominant representation, followed by Lamiaceae (14 spp.), Rosaceae (14 spp.), Fabaceae (7 spp.), Apiaceae (7 spp.), Caryophyllaceae (6 spp.), and Brassicaceae (6 spp.). Other families were represented by no more than four species only.

Based on the New Flora of Lebanon and Syria [30], all the 184 cited species were native. Among them, two species, i.e., Berberis libanotica and Pseudopodospermum libanoticum (Boiss.), were endemic to Lebanon–Syria, and another two, i.e., Arum palaestinum Boiss. and Onopordum cynarocephalum Boiss. & C.I. Blanche were endemic to Lebanon–Syria–Palestine. Also, 15 other species were endemic to the region including Turkey, Cyprus, Greece and Iraq, i.e., Acanthus hirsutus subsp. Syriacus (Boiss.) Brummitt, Achillea falcata L., Crocus graveolens Boiss. & Reut., Ferulago trachycarpa Boiss. and Valeriana erotica Christenh. & Byng.

Herbaceous species constituted the highest contribution (156 species) of the cited species, while climbers, shrubs, and trees contributed 2, 11, and 15 species, respectively.

Most plant species were cited for the treatment of more than one ailment and disease, for instance, Matricaria aurea (Loefl.) Sch.Bip treated 24 conditions, Taraxacum officinale Weber, 23 conditions and Urtica urens L. 19 conditions (Additional file 1: Table S1).

Leaves represented the plant parts most used (23%), followed by aerial parts (15%), flowers/inflorescences (14%), roots/bulbs/rhizome/tubers (14%), and fruits (10%) (Table 2). Other parts such as whole plant, seeds, bark, wood, latex, and stem were also cited. For most plants, more than one plant part was used.

Preparation methods were diverse with decoction being most common (45%), followed by infusion (25%), maceration (9%), and latex/fresh juice (9%) (Table 3). Informants also reported the use of excipients (water, alcohol, oil, honey, and eggs) and some additives (salt and sugar).

While most preparations were based on the use of a single species, some mixtures for treating respiratory and gastrointestinal conditions, in particular, were also commonly reported. For example, a mixture of Micromeria myrtifolia Boiss. & Hoben., Myrtus communis subsp. communis, Matricaria aurea, Salvia fruticosa, Alcea setosa (Boiss.) Alef., and Mentha longifolia (L.) L. was used to treat common cold, cough, flu, and sore throat. Another common mixture was made of Salvia fruticosa, Origanum syriacum, and Foeniculum vulgare Mill. This mixture was used for stomach ache and colic conditions. In the case of diarrhea, some peels of pomegranate (Punica granatum L.) were added.

The majority of remedies were prepared from fresh materials soonest after collection (60%), and some were prepared from either dried or fresh materials (31%), while a few were only used from dried materials (9%).

Medicinal formulations were administered orally (internally) (47%) in ailment categories other than dermatological problems, 8% was administered externally in dermatological ailments, while both usages internally and externally were used in 45% of cited plants.

Informants used different measuring units such as Arabic coffee cup (70 ml), glass (200 ml), soup bowl (350 ml), teaspoon (6 ml) or tablespoon (12 ml), pinch of three fingers (5 g), and handful (20 g), in addition to traditional and contemporary weighing measures such as oz (28 g) and dirham (3 g). Formulations were taken till recovery.

Interestingly, dosage of detailed formulations was particularly provided by some traditional portioners. For example, one coffee cup per day for 15 days of the decoction of Daucus carota seeds was recommended for cystitis, diuretic, laxative, diabetes, spasms, etc. (Additional file 1: Table S1). Also, a dose of two cups per day (morning and evening) for two days only of the decoction of the seeds mixed with cherry peduncles and palm dates was cited as highly efficient in the treatment of kidney stones (Additional file 1: Table S1).

Nevertheless, informants expressed concern about side effects of some species in cases of overuse (Additional file 1: Table S1). Among the most toxic species were such as Arum palaestinum Boiss., Arum hygrophilum Boiss., Eupatorium cannabinum L., Ruscus aculeatus L., Dittrichia graveolens (L.) Greuter, Ricinus communis L., Tussilago farfara L., Lonicera etrusca San., Ecballium elaterium (L.) A.Rich, Hyoscyamus aureus L., and Prunus cocomilia Ten. In particular, ingestion of a high dose of E. cannabinum, a species cited for the treatment of liver and gallbladder disorders, skin infections, colds, and fever causes tremor, delirium, and even death. Also, a relatively high frequent smoking of T. farfara leaves was perceived as a seriously harmful practice. Likewise, E. elaterium was considered highly toxic if a dose greater than one drop/day is administered as a nasal instillation. Such a dose causes serious side effects such as uvular edema, nasal and tongue edema, and other adverse effects on the voice of users. Also, a high dose of P. cocomilia seeds and young shoots used for diarrhea, skin diseases, liver cirrhosis, and diuretic was cited as toxic. With this particular example, informants reported the use of the level of bitterness as an indicator of toxicity, while berries of the L. etrusca were cited among the mildly poisonous.

Further, informants highlighted the multiuse of several cited species (Additional file 1: Table S1). The diverse uses reported were: edible for human, ritual and spiritual use, ornamental and decoration, source of natural materials (cosmetics, insect repellent and pesticide, dyes), firewood, forage, and melliferous. Gundelia tournefortii L., Pseudopodospermum molle (M.Bieb.) Kuth., Eryngium creticum, Rhus coriaria L., and Cichorium intybus L. among others (n = 84 species) were cited as edible plants. Further, Anchusa hybrida Ten., Calicotome villosa (Poir.) Link and Cedrus libani were among the most frequently cited as melliferous plants (n = 33). Also, Cistus creticus L. and Chrozophora tinctoria (L.) A. Juss. were among species cited for forage. Informants also reported that treatment was done by oneself in common ailments such as common cold, indigestion, mosquito bite, and abdominal pain.

Quantitative indices presented in Additional file 1: Table S1 and Fig. 2 revealed that species of highest FC values were Berberis libanotica, Hyoscyamus reticulatus, Dittrichia viscosa, Echinops spinosissimus, and Urtica dioica.

FC values for the top 15 species

Additional file 1: Table S1 and Fig. 3 also show that RFC ranged between 0.05 and 0.48 with Dittrichia viscosa scoring the top value. Other high RFC values were achieved by Capparis spinosa (0.44), Micromeria myrtifolia (0.41), Centaurea iberica Trevir. ex Spreng. (0.40), and Daucus carota L. (0.38). Species of low RFC included Blitum virgatum L. and Aristolochia sempervirens L. having the value of 0.05.

FCR values for the top 15 species

Scores of UVs ranged between 0.10 and 3.86 with Dittrichia viscosa achieving the highest score (UV 3.86). The plant was cited to treat a wide range of diseases and ailments including skin diseases (wounds and infections), respiratory (bronchitis), gastrointestinal and liver (stomach ulcers), diabetes, and rheumatism. Daucus carota followed with a score of UV 3.85 cited for the treatment of a less number of ailments (Additional file 1: Table S1 and Fig. 4). On the other hand, Valeriana rubra L. and Ranunculus ficarioides Bory & Chaub. achieved the lowest values (UV 0.10).

UV values for the top 15 species

Wide diversity of diseases and ailments was recorded and grouped into 14 use categories (Table 4). Gastrointestinal system and liver diseases were treated by 16% of the cited plants. This was followed by skin and related symptoms (13%), respiratory system diseases (9%), central nervous system (7%), and blood–hematopoietic system (7%) (Table 4). Accordingly, the FIC values reflecting the agreement between informants on the use of a species in the treatment of specific disease categories fell in the 0.62–0.02 range.

The highest fidelity level (100%) was recorded with Berberis libanotica, Hyoscyamus reticulatus L., and Dittrichia viscosa which were frequently cited to treat specific ailments and diseases including respiratory, skin, gastrointestinal, blood–hematopoietic system, diabetes, and rheumatism and ranged between 90 and 95% for the rest of highly cited plants (Additional file 1: Table S1) (Fig. 5).

FL values for the top 15 species