Fifteen small communities distributed in five districts in the northern West Bank in the Palestinian Authority (PA) were selected for this study (Table 1 and Figure 1). Each of the five districts was represented by one or more villages (communities) located mainly within homogenous mountainous, rural areas. The environment is mainly semi-arid, and the prevailing socio-economy is agropastoral. Despite its small geographical area, the West Bank is characterized by a large variation in topography (Figure 1). This variation is directly reflected on climate and the distribution and diversification of agricultural patterns, from irrigated agriculture in the Jordan Valley (the lowest area in the world) to rain-fed farming in the mountains 20. The West Bank is divided into four major biogeographical zones: semi-coastal zone, central highlands, eastern slopes, and the Jordan Rift Valley. The study sites were mainly located in the first three of the above-mentioned zones. The Semi-coastal and central highlands zones represent more than 60 per cent of total area of the West Bank. All rain-fed and nearly half of irrigated land are within this zone. About 105, 000 hectares of fruit trees, namely olives, grapes, almonds, and other deciduous fruit trees are planted in this zone. Most of the winter crops, all summer crops and rain-fed vegetables are grown in this zone. Also, most sheep and goats flocks, cows herds and nearly all poultry farms are located in this zone. The Eastern Slopes zone represents the semi-desert climate as transitional zone between the true Mediterranean and desert climate. It is located between the Jordan Valley and the Central Highland Regions. The steep mountains with little rainfall that predominate in this region make it an almost semi-arid to desert zone. It is suitable for grazing and, to a certain extent, is utilized for field crops varieties that survive with the average yearly rainfall of 150–300 mm such as barley and wheat. Approximately 53.3% of the total population in the West Bank lives in rural areas and refugee camps and the remaining 46.7 of the population in urban areas. The Palestinian per capita GDP averages around US $1,500 annually, mostly coming from service and day labor sector, with agriculture making up between 18 and 30 percent and industry making up very little. Ecological and economic characteristics of the studied localities are outlined in Table 1.

Interviews were conducted during spring and summer of 2006, with approximately 20–80 informants in each district (total number of interviewees: 190, 138 females, 52 males) (Table 1). They were mainly selected using snowball techniques 27. Informants with a sound traditional knowledge of useful wild plants, mostly either native born or had been living in the region for more than 30 years, were interviewed. Informants were between the ages of 30 and 95 years with an average age of 52 years.

A clear expression of consent was also obtained before each interview. Through this field study, the ethical guidelines adopted by the International Society of Ethnobiology 28 were observed.

Questions addressed to the informants about wild food consumption were mainly focused on common local name, knowledge about past and present use, mode of consumption and preparation, parts of the plants used, the manner of their preparation and administration, procurement method, place of collection and habitats, threats and conservation status, date/season of collection, method of storage, and period of storage.

Voucher specimens were deposited at the herbarium of Biodiversity and Environmental Research Center at Til, Nablus (West Bank, PA). Identification was carried out using the Flora Palaestina 29 and other available pictorial floras and taxonomic references 30313233.

The flora of the study area provides diverse useful species. A total of 100 wild edible plant species are gathered and consumed in the study areas. These are classified among 89 genera and 35 families (Table 2). Seventy six of these plants were mentioned by 3 informants and above and were distributed across 68 genera and 26 families (Additional file 1). Plants that were mentioned by less than 3 informants (24 species, 24 %) were excluded from further discussion (Additional file 2).

Within the edible plants, leaves (24 %), and stems (21 %) were the plant parts most widely used (Figure 2).

The wild edible plants are consumed in many different ways and are prepared using diverse recipes according to local traditions. Some of them are eaten raw, and some others eaten cooked and thus require a more or less complex preparation process (Additional file 1). It is obvious that raw recipes predominate in the modes of consumption with a total percentage of 89 % in the five surveyed areas, while cooked edibles follow with the relatively high percentage of 77 %. This is in agreement with what people think about Mediterranean diets and that Mediterranean people always portrayed eating vegetables raw 36. However, the high percentage of cooked edibles may be attributed to the change of the socio-economic context of rural areas around the country. Nowadays, people do not spend as much time outside in the natural environment as they used to do in the past in order to feed with raw vegetables, and therefore, since they are influenced by contemporary dietary trends of cooked food, edible plants collected from the wild are brought home for more elaborated cooking recipes.

Based on number of informants who mentioned the plant for food purposes at different localities (Additional file 1), the following were the most utilized plants (cited by more than half of the maximum number of informants who reported a plant for any food use) (11 species): Majorana syriaca, Salvia fruticosa, Malva sylvestris, Cyclamen persicum, Gundelia tournefortii, Foeniculum vulgare, Arum palaestinum, Rumex acetosa, Matricaria aurea, Micromeria fruticosa, and Trigonella foenum-graecum. These plants have been traditionally used in the five areas.

When the five plants most times quoted in each of the seven Mediterranean countries studied by Hadjichambis et al. 6 are compared with the five plants most quoted in the Palestinian Authority in this study (Table 3) it became clear that within the eight countries the wild edible plants most times quoted show great variability. Again, in the PA, a different group of five species is the most popular, showing only a few similarities with other countries as in the case of Malva sylvestris (two countries). According to that data we agree with Hadjichambis et al. 6 suggestion that there is no common Mediterranean cultural heritage in the selected countries regarding the gathered wild edible plants, since even though the most quoted taxa are sometimes the same, the cultural importance of these species is very different in the cuisine.

Figure 3 lists, in order of importance, the twenty most culturally important species in the Northern West Bank according to the mCI, and their CI values in each survey area. It is clear that within the five study localities the plant species with highest CI values show large similarity.

As it is expected, these plants include some of the most deeply rooted plants in the Palestinian traditional culture and ethnobotany, namely Majorana syriaca (Za'tar), Salvia fruticosa (Mariamieh), Malva sylvestris (Khubbaizeh), Cyclamen persicum (Za'matoot), and Gundelia tournefortii (Akoob). All these plants are used as food and medicine (Additional file 1). Some of these plants are considered holy plants being mentioned in the holy books (e.g., Majorana syriaca in the bible), or sacred/blessed being mentioned in legends linked with holy people (e.g., Salvia fruticosa and Virgin Mary; the plant is even called Mariamieh after her). Salvia fruticosa was also recognized by Palestinian Muslims in Northern Israel for its ritual importance in cemeteries and funerals 38. Majorana syriaca, Cyclamen persicum, and Gundelia tournefortii have been used for a very long time to prepare traditional recipes 25. A few of these plants are even mentioned in local folkloric songs and proverbs (Malva sylvestris, Gundelia tournefortii, Salvia fruticosa) 25.

The 20 most significant species (Figure 3) include fruits (Crataegus aronia, Ceratonia siliqua), seasonings (Rhus coriaria, Foeniculum vulgare), herbal teas which are used in general as a digestive (Salvia fruticosa, Matricaria aurea, Anisum vulgare, Trigonella foenum-graecum), and vegetables (Malvasylvestris, Cyclamen persicum, Arum palaestinum, Gundelia tournefortii, Salvia hierosolymitana, Cichorium pumilum, Rumex acetosa). For the five areas as a whole, the species used as vegetables were very important, with 4 species in the top 10. Two species used for seasoning and four for herbal tea also rank highly. Fruits were clearly much less important, Ceratonia siliqua ranking fifteenth and Crataegus aronia ranking eighteenth. Other taxa were less important (Additional file 1).

As it is expected, indigenous people do not eat all wild edible plants present in their environment but only a small part of the local flora. What makes the difference is the cultural decision that is behind each group of gathered food plants 19.

Table 4 also shows the number and percentages of species (% of spp.) and of use report (UR) among each food category at each survey site, which indicate that vegetables were the most important category in all areas (% of spp. = 69.7; % UR = 55.4), followed by herbal teas (35.5; 16.6), plants used for seasoning (26.3; 13.7), and fruits (21.05; 11.2).

Figure 3 indicates cultural importance index (CI) of the 20 most relevant species in the study are in descending order by mean value (mCI).

Figure 3 also shows appreciable differences among the CI values of the 20 most relevant species obtained in the different areas. All the ten species with the highest mCI, were cited in all five areas. Moreover, most were important in every region. The next ten species were also used at all study sites, e.g., Matricaria aurea, Rumex acetosa. A common cultural background may explain these similarities. Interestingly, the CI values for edible species (9/20) in Qalqilia, and Salfit (5/20) are generally higher than for species in other areas (Figure 3). This can be attributed to the fact that local knowledge of wild edible plants and plant gathering are more spread in remote or isolated areas 34. To examine this supposition further, the CI values for all species in each area (mCIa) as a measure of botanical knowledge were calculated. The mCIa value for Salfit (0.36) was more than that of Tulkarm (0.26). This is an appreciable difference in knowledge of edible plants among different human groups. Qalqilia, a neighboring territory had also a comparably high mCIa value (0.31), followed by Jenin (0.25), and Nablus (0.19). Although Tulkarm and Qalqilia (both semi coastal areas) are neighboring territories sharing a similar environment, the difference is significant. This can be explained by greater loss of knowledge in the former. Moreover, Qalqilia and Salfit were partly isolated either due to movement restrictions being located in an area of extensive Israeli settlement activities, in case of Salfit, or isolated by Israeli separation/security wall in case of Qalqilia.

A comparison between the most quoted food botanical families in the different communities is presented in Figure 4. The data were expressed as percentage of the wild food taxa belonging to a given family out of the total number of quoted taxa recorded in the related area. Asteraceae (13 species, 17%), Fabaceae (9, 12 %), and Lamiaceae (8, 11 %) were more often quoted as wild edible plants in all localities than were other families, followed by Rosaceae (7, 9 %), and Brassicaceae and Apiaceae (5, 5 %). The last three families were more quoted in Nablus than in other localities. Other families showed no or low representation (0–3 spp.) in the different localities (Table 5). Our results are therefore in agreement with those of Hadjichambis et al 6, who also found Asteraceae, Lamiaceae, Rosaceae, and Apiaceae to be among the five families with the greater number of representative wild edible plants in the Mediterranean countries they studied. These are known to be big families with many representatives in the Mediterranean area and some of which are common plants 6. Hence our results confirm that people tend to use preferably the plants that are easily available to them. These results are in agreement with those of Bonet and Valle's 15, Bonet et al. 39, Johns et al. 40, and Stepp and Moerman 41, which affirmed that the more common a plant (family or species) is in an area, the greater is the probability of its popular use.

Although a family's cultural importance correlates strongly (r = 0.615) with the number of species in each family (Figure 5) a regression analysis was carried out to confirm statistically which families had higher values than expected for the number of species 34. Figure 5 indicates that the plant families with more than 5 species and greater cultural importance as wild food in the Northern West Bank were: Lamiaceae, Asteraceae, Fabaceae, Apiaceae, Rosaceae and Cruciferae. However, only the Lamiaceae attains a significantly higher figure for cultural importance than that expected for the number of species. This fact remarks the high significance of vegetable and herbal tea category in most of the survey areas.

A local particularity that is worth mentioning is that Lamiaceae is the most important family in Salfit, according to its CIf (3.21, see Table 5). This is due to the higher relevance of plants used as herbal tea in this area, both in relative number of species % of spp. and UR, as shown in Table 4 and Additional file 1.

From the 103 edible plants recorded, 64 (62 %) have been cited to be used for food as well as for medicine (Additional files 1 and 2). These are food plants that receive recognition as medicinal in the Traditional Arabic Palestinian Herbal Medicine and represent a part of the Palestinian medicinal ethnoflora 24. Overlapping between food and medicine is well known in traditional societies 9 and represent an often neglected field in ethnopharmaceutical research 6.

No clear dividing line between food and medicinal plants usually exists, especially in indigenous and local traditions. Food can be used as medicine and vice versa. Still certain wild edible plants are used because of their assumed health benefits and thus can be called medicinal foods 42.

For example, the leaves of Arum palaestinum is consumed fried using olive oil because it is perceived to protect from colon cancer.

The relatively common use of Lamiaceae and Asteraceae as food as well as medicine in the present study is in agreement with the findings of a similar study on food plant consumption in seven Mediterranean countries 6. This can be attributed to the phytochemical features of many species of these families (i.e., presence of essential oils in Lamiaceae, and sesquiterpene lactones in Asteraceae).

It is worth mentioning that previous ethnobotanical field surveys 1824 have revealed that healthcare practices of the household using preparations based on plants are usually administered by women. However, most studies have advantaged the 'medicine of healers' instead of the 'medicine of the households' 4324.

The study revealed that 42 % of the wild edible plant species were gathered from natural shrub lands, followed by agricultural fields (35 %), roadsides (14 %), and natural forests (9 %). Wild edible plants are facing threats in their natural habitats from various human activities. The level of impacts of these activities varied from place to place. The local people's perception on the activities more threatening to wild edible plant species (over-grazing, agricultural land expansion, over-harvesting, uncontrolled fire setting and fuel wood collection) for each factor (total some of each factor), varied among informants of different communities (Table 6).

However, the overall rating for all communities showed agricultural expansion as the main threat to wild plant species, followed by over grazing and over-harvesting. As to the protection status, most of the wild species in these areas have no protection. However, very few economic plant species (e.g., Majorana syriaca) are now cultivated and marketed by some farmers. This shows that acquisition of economic benefits from species might promote local people's interest in conservation and maintenance of such locally important and threatened species 4.