Data from 292 taxa belonging to 85 botanical families were collected in the present study, resulting in a total of 1,965 use reports (UR). All the data grouped by uses are included in the taxa catalog (see Additional file 3).

Regarding number of taxa, the best-represented families are Asteraceae (9%), followed by Poaceae (8%), Rosaceae (7%), Brassicaceae (5%), Lamiaceae (5%), Fabaceae (5%) and Apiaceae (5%). Regarding use reports, the same families are the most reported (in a different order) (Table 1).

These results align with studies conducted in other agricultural regions of the Mediterranean basin [23, 56]. Furthermore, apart from Brassicaceae, the best-represented families are consistent with those observed in other surveyed regions of the CLA, owing to their considerable diversity and widespread distribution [22, 57, 58].

Some quantitative ethnobotany indexes concerning 10 territories (including the one here studied) of the CLA are presented in Table 2. The ethnobotanicity index (EI) for the studied area is 25.50%, indicating that approximately one-quarter of the plants in the area have been reported as useful by the informants. This places it in an intermediate position within the range of values obtained for other CLA. The informant consensus factor (FIC) of medicinal information obtained (0.74) is among the lowest values observed in the quoted areas. However, these are common values in rural areas of the Mediterranean Basin, such as the Greek Aegean Islands (0.72) [59] or northeastern Algeria (0.72) [60]. While the interpretation of FIC values should be approached cautiously, taking into account factors like culture, social context and methodology, the ability to compare these values on an equal footing leads us to believe that significant local ecological knowledge is still preserved in agricultural periurban regions like this one.

Our informants mentioned 117 species with medicinal uses, representing 45 botanical families and 451 use reports. Among these, 99.12% are referring to human medicine, 0.44% to veterinary medicine and an additional 0.44% to both contexts. The average number of medicinal taxa cited by informant stands at 1.41, exhibiting striking similarity to other urban agricultural areas (1.28) [23]. Furthermore, these figures approach those derived from rural territories within the CLA surveyed [45, 46]. This underscores the assertion presented in Gras et al. [22] that ethnobotanical knowledge is still relevant in industrialized areas, even in comparison with non- or less-industrialized territories.

The 20 most cited species are included in Table 3. They represent the 52% of medicinal use citations. Thymus vulgaris is the most cited taxon, with a RFC of 0.205. Most of these taxa are among the most quoted in the rest of the CLA [22, 58, 63]. Furthermore, the presence of species abundant in ruderal environments stands out, such as Malva sylvestris, Matricaria recutita or Foeniculum vulgare subsp. piperitum. These findings align with those observed in other European periurban agricultural areas [23]. In addition to this, the medicinal use of Cynara scolymus is notable, as it is a cultivated species with a rich agricultural tradition in the area. In total, species cultivated for food that also have medicinal uses comprise 39%. (Fig. 2). These could be considered as folk functional foods, which are further discussed below.

Sources of medicinal use (left) and food use (right) taxa reported

Concerning botanical families, Lamiaceae is the most cited (19%), followed by Asteraceae (16%), Apiaceae (7%) and Rosaceae (5%). These results agree with the general family distribution of the area. Lamiaceae and Asteraceae have a high number of representatives in the Mediterranean flora and Rosaceae include some fruit trees. The three of them agree with other ethnobotanical studies of Mediterranean areas [6]. In other regions of the Mediterranean basin, the Apiaceae family similarly emerges as one of the most prominently represented in terms of medicinal use reports [60, 66].

The results from the most reported parts align with those observed in other regions of the CLA, irrespective of geographic conditions [63,64,65]. The aerial parts (including the young aerial, sterile aerial, flowering aerial and fructified aerial parts) are the most frequently cited, accounting for 46% of UR. Fronds and leaves constitute 23% of UR, while fruits (including fruit juice like, for instance, from Citrus limon) comprise 12%. Generally, these are the plant parts that allow an easier identification to informants and that present less collection and conservation difficulties.

The most treated disorders are those referred to digestive system, accounting for 37% of the total. Respiratory system disorders represent 13% of the total (Fig. 3). The same findings have also been highlighted by several studies conducted in CLA [22, 57, 58] and all around Mediterranean basin [6, 23, 56, 60]. Most of the remedies concern the treatment of unimportant pathologies [63]. The most cited digestive ailments are related to diuretic and hepatoprotective uses. In terms of respiratory diseases, colds and coughs are predominant.

Systems and disorders addressed with medicinal plants in the area studied (UR). D digestive system disorders, R respiratory systems disorders, CB circulatory system and blood disorders, SS skin and subcutaneous system disorders, S sensory systems disorders, NM nervous system and mental disorders, PI pain and inflammations, G genitourinary system disorders, II infections and infestations, UN unspecific disorders, MS musculoskeletal system disorders, EM endocrine system and metabolic disorders, N nutritional disorders, IN immune system disorders and neoplasia, UK unknown by the informant, PR pregnancy, birth and puerperal disorders, T traumatisms, P poisoning

The most cited taxon for digestive system disorders is Cynara scolymus, primarily used as a hepatoprotective. This species is extensively cultivated within the surveyed area. This fact reflects the idea that plants used in folk medicine are obtained from places close to those where the users live [3, 4, 54, 58].

When the index of medicinal importance (MI) is calculated, sensory system disorders have the highest results. As an example of sensory system disorders, it is relevant to mention eye problems, which are treated with some species such as Thymus vulgaris (7 UR), Matricaria recutita (6 UR), Ruta graveolens (5 UR) or Sambucus nigra (5 UR).

Regarding the pharmaceutical form, tisane—including decoction and infusion—represents 41% of the total forms reported, in line with the findings of other studies in the Mediterranean basin, including Spain, Morocco, Algeria and Italy [3, 6, 23, 56, 60, 66]. Direct use represents 16%. Thus, the simplest pharmaceutical forms employed are the most common, as indicated by Parada et al. [67]. Likewise, it is noteworthy to highlight the 19% of use reports cited (the second most represented category) where the pharmaceutical form is either not specified or is unknown by the informant. Interestingly, these reports are primarily not associated with the most frequently mentioned medicinal uses (Fig. 2). This observation might suggest that informants are aware of the medicinal properties of certain plants but are not actively using them, potentially due to a decline in traditional knowledge. Nevertheless, further investigation into this aspect would be necessary in future surveys.

In terms of medicinal mixtures, 18 recipes have been inventoried (54 UR, involving 34 taxa). The species most commonly employed include Rosmarinus officinalis, Thymus vulgaris and Olea europaea subsp. europaea var. europaea. These mixtures are predominantly employed for pain relief purposes, encompassing analgesic, antalgic and anti-inflammatory properties, along with applications for treating colds and tetanus. Specifically, concerning the latter therapeutic application, informants refer to a practice known in Catalan as “fer una palla” (literally translating to “make a straw”). This method involves utilizing a straw made from Triticum aestivum combined with olive oil (Olea europaea subsp. europaea var. europaea). This remedy was used for instances where animals or humans sustained puncture wounds. In this approach, oil is inserted into the straw and positioned vertically over the wound. The lower end of the straw is ignited, causing the oil to heat and subsequently trickle onto the wound, facilitating its healing process.

Food uses are the most reported in this area: 1247 UR of 171 taxa belonging to 55 botanical families. These findings show a distinct pattern in comparison with other ethnobotanical studies on useful plants, where medicinal uses tend to surpass food uses [57, 58, 64]. However, this aligns with a study by Gras et al. [22] in a semirural area near industrial zones. While interview biases might exist, this reflects the agricultural importance within the local community.

Regarding their usage, 85.19% of these taxa are for human consumption, 14.58% for animal feed, and 0.23% are used for both human and animal consumption. On average, each informant cites 2.06 food taxa, with an FIC of 0.86—both values are higher, compared to those calculated for medicinal uses. Based on informant responses and participatory observation, it has been determined that among the mentioned plants, 52% are cultivated and the rest are wild or restored to a natural state (Fig. 2).

The Rosaceae family leads in terms of use reports (11%), followed by Asteraceae (10%), Solanaceae (8%) and Brassicaceae (8%). With the exception of Solanaceae, these families align with the broader family distribution in the area. Notably, these families hold considerable importance for food applications in Mediterranean countries like Spain, France or Italy [68,69,70].

The 20 species with the highest use reports are listed in Table 4. Notably, the most frequently cited taxa are cultivated species. This observation aligns with the logical assumption that cultivated species are primarily consumed as food and have been reported accordingly. Among the non-cultivated species, Thymus vulgaris, Portulaca oleracea, Foeniculum vulgare subsp. piperitum and Borago officinalis hold the 9th, 15th, 17th and 19th positions, respectively. It is worth mentioning that these non-cultivated species emerge as prominently cited, echoing findings from an ethnobotanical review of wild edible plants in Spain [70] and other Mediterranean areas [71]. Additionally, Thymus vulgaris has consistently appeared as one of the most cited species for food use in studies across various Mediterranean regions [57, 63].

Interestingly, Portulaca oleracea is linked with crops and is considered a weed by farmers. Recently, it has gained attention as a functional food due to its chemical composition [72]. Another significant species is Ceratonia siliqua (13 use reports, 1% of total), once a fading crop in Catalonia used for human and animal consumption. However, its nutritional value is still recognized, and the demand for it as human food is rising due to the trend for natural products [73]. Both species have valuable economic and environmental potential, making them worthy of market exploration for future research.

Fruit and infructescence are the most used plant parts (36%), followed by leaves (21%), aerial part (15%), and flowers and inflorescences (7%). Regarding the mode of consumption, the most common way is fresh (28%). The plants boiled (11%) and used as a condiment (8%) constitute the following categories.

Regarding food mixtures, the predominant approach is focused on food preservation, accounting for 63% of the recipes. For instance, some recipes involve preserving olives (Olea europaea subsp. europaea var. europaea) in brine, along with other species like Ceratonia siliqua, Satureja montana, Foeniculum vulgare subsp. piperitum, Allium sativum, or Citrus limon. Likewise, an ancient Catalan practice called “arrop,” akin to confiture, is used to preserve fruits and vegetables. This involves boiling plant parts in wine [74]. Informants add sugar and fruits like Prunus avium, Solanum melongena, Vitis vinifera (grapes), Cucumis melo subsp. melo, Citrus limon and Citrullus lanatus. Typically, this approach involves repurposing fruits or their parts that are usually discarded due to their unappealing appearance (Fig. 4).

On the left, seasoned olives prepared with a mix of species. On the right, watermelon “arrop”

Concerning animal fodder (Fig. 5), the Fabaceae family is most frequently mentioned (34%). The most cited taxa are Ceratonia siliqua (14%) and Medicago sativa (14%). Ceratonia siliqua, as mentioned earlier, was a widely cultivated crop in the Catalan region, and it was provided to horses and draft animals to supplement their energy intake. The commonly used plant parts include the aerial parts (39%), fruits (21%), raw or powdered seeds (17%) and underground parts (9%). Notably, 45% of the taxa used for animal feed are also cultivated for human consumption, suggesting that animals are often fed with discarded plants or parts. Of the taxa, 27% are intentionally grown for fodder, while the remaining 27% are wild plants.

Botanical families and taxa for animal feed (UR)

In recent times, there has been a significant interest in food products that perform some healthful function in the human body [75,76,77]. In ethnobotany, the interface between the food and medicinal uses of plants is very permeable, so that many foods heal and many medicines nourish. It is what is called a popular, traditional or folk functional food [78,79,80]. In this study, 56% of reported medicinal plants also contribute to human nutrition, similar to findings in other Mediterranean studies [80].

The most relevant species identified as folk functional food are presented in Table 5. Thymus vulgaris occupies a preeminent position in this ranking, in line with findings by Vallès et al. [79] and Rivera et al. [71]. Except for Allium cepa, the remaining species are also prominent in terms of medicinal uses (as discussed earlier), suggesting a perceived continuum between medicinal and food plants [23, 77, 80, 81].

When comparing the list of folk functional food in our study area with the encompassing CLA [79], it emerges that 77% of taxa have already been documented in prior studies, indicating their concurrent roles in both medicinal and food uses. Conversely, it is noteworthy that species such as Ceratonia siliqua, Anethum graveolens or Cucurbita maxima are being highlighted for the first time within the context of the CLA as folk functional food.

This category encompasses uses that are neither medicinal nor related to food. A total of 267 use reports are collected, concerning 111 taxa from 46 families. The average number of taxa mentioned per informant is 1.34. The most used taxa in this category are outlined in Table 6. The most frequently taxa cited are Arundo donax. This species is associated with agricultural management, particularly for supporting the growth of climbing cultivated plants. Arundo donax is also prominently cited in other regions with similar characteristics [22, 63]. Within this category, Poaceae emerges as the family with the highest UR (18%), followed by Fabaceae (12%). These families are also well represented in the broader distribution.

The most frequently mentioned uses are related to agrosilvopastoral applications (28%), followed by the creation of artistic works (11%) (Fig. 6). The significant use in agrosilvopastoral management is influenced by the area's agricultural nature. Some subcategories are incorporated within the agrosilvopastoral category, and the top cited use is the crafting of agricultural tools (13%). These tools primarily serve two purposes: (1) to support the growth of cultivated species (mainly tomatoes, beans and peas) using exclusively Arundo donax stems, and (2) for tying other cultivated species (mainly lettuce, chards and cabbages) with materials such as Spartium junceum, Phormium tenax or Juncus acutus. Other subcategories within the agrosilvopastoral category also hold significance due to their historical and current applications in non-intensive agricultural practices: ecosystemic balance (5%) involves growing certain species beneficial to crops; specific plants, like Symphytum officinale or Equisetum arvense, are used as natural fertilizers (4%); some contribute to the landscape's formation (3%) as natural enclosures or erosion-protecting soil barriers, such as Opuntia maxima (2 UR); some plants function as natural pesticides (2%) or are employed for mulching (1%), which entails applying crushed plant material to the ground to shield it from harsh weather conditions (excessive sun or frost).

Other uses categories and subcategories (UR)

The second most frequently mentioned category among other uses is the creation of artistic works. These mostly involve the crafting of “paneres artístiques” (“artistic baskets”) (Fig. 7), which are imaginative murals constructed from plant material. This practice is deeply rooted in local tradition and culminates in an exhibition and competition held during the Gavà Asparagus Fair, a spring event that has taken place annually since 1932. Around 20 distinct species are cited for this creative purpose.