Beyond food and medicine, but necessary for life, too: other folk plant uses in several territories of Catalonia and the Balearic Islands

Background Ethnobotanical academic research, particularly in European industrialised countries, has been, and is, mostly focused on folk uses of food and medicinal plants. Nevertheless, other uses, as may well be supposed, account for a significant portion of these folk uses. In the Catalan linguistic domain, a considerable amount of ethnobotanical work has been produced, but to date almost nothing has been published on these other plant uses. Methods We basically used the method of semistructured interviews to collect data on names, knowledge and use of plants in the above-mentioned fields from 759 informants in three Catalonian (Alt Empordà, Montseny and Ripollès) and two Balearic (Formentera and Mallorca) areas. We identified the plants quoted by the informants and prepared herbarium vouchers. We analysed and compared the results obtained. Results Information has been collected on 401 genera, 552 species, 81 subspecies and four varieties, belonging to 122 families, totalling 4137 use reports for popular non-food and non-medicinal uses (classified in 14 modalities), and designated with 1303 folk Catalan names. The informant consensus factor is 0.87, accounting for a consistent and robust dataset. Conclusion Contrarily to what could be thought a priori, and irrespective of the fact that some uses are declining or changing, non-medicinal and non-food folk plant uses strongly persist in the territories considered, are highly considered by their practitioners, and may even imply some economic revenues.


Background
When coining the term ethnobotany, Harshberger [1] considered as basic points for the newly named science "elucidating the cultural position of tribes who used plants" (where, nowadays, 'tribes' is replaced by 'human groups' , [2]), "clarifying the past distribution of plants", "determining trade routes" and "suggesting new current production lines" for useful plants. For Portères and Barrau [3,4], ethnobotany is a discipline located at the crossroad between natural and human sciences studying the behaviour of human societies with regard to plants. Other authors state that ethnobotanical research rescues and updates the history of plants in human societies through time and space [5].
Even if ethnobotany deals with all kinds of plant uses, at least in western European countries, ethnobotanical research focused on food and medicinal plants is by far the most dominant, what can be verified when surveying the articles that have appeared in relevant journals. Such a situation can be explained by two kinds of reasons. On the one hand, food and medicine are the two plant folk applications more directly linked to human health, so that they are maintained at a relatively high rate even in industrialised societies. Conversely, these countries have undergone a rather deep process of acculturation, in the sense of adopting so-called modern habits in detriment of traditional culture [6], which implied that rural communities abandoned a great deal of traditional practices linked to plants, because they are much less necessary (if necessary at all) nowadays than in the first half of 20 th century. On the other hand, the above-quoted food and medicinal properties are those which most likely can lead to the development of new commercial sources of welfare products (see e.g., [7]). Some non-food and nonmedicinal popular uses are slightly better preserved than most of them, such as basketry [8] and cosmetics [9,10], the latter being, in fact, very closely linked to medicinal ones. Some specific papers with ethnobotanical focus have been devoted to these other plant uses in European countries (e.g., those quoted for basketry and cosmetics, as well as [11][12][13][14][15][16]). Additionally, some compilation work, rather addressed to folk knowledge vulgarisation, contain information on these plant utilisations; as an example the first volume of the ongoing Spanish Inventory of Traditional Knowledge related to Biodiversity [17] provides information on all kinds of plant uses, including those dealt with in the present paper. In any case, even taking into account the above-quoted contributions, this approach still remains quite scarce.
The research on ethnobotany in the Catalan linguistic domain has been intense in the last 25 years. This research mostly comprises data on food and medicinal (including veterinarian) plant uses, as well as studies linked to agroecosystems (mostly homegardens) and to ethnoecological questions (cf. [10,18], and references therein). Only very rarely other plant uses have been addressed [19,20], although, throughout our research, we have maintained the conviction that a robust pool of knowledge on these uses still exists. Taking this into account, the aims of the present paper are: 1) to provide an overview on non-food and non-medicinal popular plant uses in five Catalan language territories, three in Catalonia and two in the Balearic Islands; 2) to evaluate to what extent these uses are persisting and how are they currently considered by their practitioners.

Study areas
We performed interviews in five territories located in two large areas of the Catalan linguistic domain, three in Catalonia (Alt Empordà, Montseny, Ripollès) and two in the Balearic Islands (Formentera, Mallorca), with the aim of comparing a continental place and an insular one (Fig. 1). The Catalonian areas comprise from plain to high mountains, and the Balearic ones involve two islands.
Alt Empordà (AE) is a district (comarca in the Catalan language) of 1358 km 2 and 140,214 inhabitants [21] living in 68 municipalities. The climate is mainly coastal Mediterranean. The vegetation is distributed in an asymmetrical form in two biogeographical regions, Mediterranean, largely dominant, and Eurosiberian, in certain mountainous areas, reaching 1443 m a.s.l.
Ripollès (RI) is a district occupying an area of 956.6 km 2 and having a population of 25,700 inhabitants [21] distributed in 19 municipalities, with a high percentage of the population inhabiting small villages and isolated houses. Located in the eastern Pyrenees, it has a high mountain climate with Mediterranean influence. The flora and vegetation are mostly Eurosiberian, with some Boreoalpine zones in mountain areas reaching 2909.8 m a.s.l. Montseny (MO) is a mountain massif with a maximum altitude of 1706 m a.s.l., with an area of 826 km 2 and a population of 105,000 people [22]. The climate is basically Mediterranean (including mountain Mediterranean). The vegetation belongs to the Mediterranean and Eurosiberian regions. Formentera (FO) is the smallest of the four inhabited Balearic Islands, occupying 82 km 2 , and has 11,545 inhabitants [23] living in nine population centres, all belonging to one municipality. Its maximum altitude is 195 m. The climate is Mediterranean with an arid tendency. The vegetation landscape is basically coastal Mediterranean.
Mallorca (MA) is the biggest island in the Balearic archipelago, and the seventh largest in the Mediterranean sea, with the highest altitude at 1445 m. It has an extension of 3622.54 km 2 and population of 858,313 inhabitants [23]. Its climate is typically Mediterranean. The vegetation belongs mostly to the Mediterranean and, to a small part, to the Eurosiberian biogeographic regions.

Informants
Information was obtained from 769 informants, selected on a snowball basis [24] for general ethnobotanical prospections in each of the areas studied. Of them, 510 were from Catalonia and 259 from Balearic Islands, distributed as follows: 160 from RI, born between 1915 and 1988, with an average age of 71.6 years; 178 from AE, with a mean age of 69.44 years, ranging from 23 to 95; 172 from MO, with a mean age of 66, ranging from 31 to 96; 235 from MA, with an average of 76 years, born between 1906 and 1981; and 24 from FO, born between 1920 and 1943. Concerning gender, 445 interviewees were women (57.87 %) and 324 men (42.13 %). Ethnobotanical interviews were performed with a total of 769 informants (see Results and discussion section for details on distribution, gender and age). Taking into account the Code of Ethics of the International Society of Ethnobiology [25], we asked the interviewees' informed consent to participate in the survey, to register the interviews, to take pictures and to use their images and information. The method used was basically the semistructured interview [26], with special care taken in not asking direct questions, which could coerce, condition or influence the informant's answer. In several occasions group interviews were carried out, separating the answers of the different interviewees. Whenever possible, we collected the plants in question together with the informants or we observed with them those they had preserved at home or their preparations or the objects elaborated with them. The interviews, developed in Catalan, the common language of both interviewers and interviewees, were registered, also with the informants' agreement (which was also solicited for taking pictures).
Plants were identified at specific or infraspecific levels with the aid of the Flora manual dels Països Catalans [27], and for family assignation we followed the Angiosperm Phylogeny Group ( [28]; http://www.mobot.org/ MOBOT/research/APweb/), as currently reflected in The plant list (http://www.theplantlist.org), also devoted to gymnosperms and ferns. Vouchers of every taxon with associated information have been prepared, collected following the legislation and avoiding protected areas, and deposited in the herbaria BCN, of the Centre de Documentació de Biodiversitat Vegetal, Universitat de Barcelona, and BC, of the Institut Botànic de Barcelona.

Databasing
Once in the laboratory, the interviews were transcribed and introduced into our research team's database (www.etnobotanica.cat, not open to public access, but punctually consultable on request to the corresponding or to the last authors). This database contains all ethnobotanical data (on medicinal, food and other uses) from our group and allows us to manage the results, to perform some calculations and to establish comparisons. Taking Cook's Economic Botany data standard as a departing point [29], a huge effort to establish and nuance use categories (as well as parts of plants and kinds of preparation and use, the latter not relevant here, but in medicinal and food uses) has been performed, and it is reflected in Table 1.

Statistical methods
All calculations were carried out using Excel (Microsoft Excel 2007) and the program XLSTAT (v. 2007.5, Addinsoft SARL) was used to carry out the Chi-square test in order to check the statistical differences in the use categories among the four studied territories.

General data
The 769 informants reported 401 genera (34 of the taxa reported have only been determined to the generic level), 552 species, 81 subspecies and four varieties, belonging to 122 families. The taxa collected, their folk names and uses, the territories where they are recorded, the parts of plants employed and their use frequency are presented in Table 1, placed as an appendix. The number of taxa with such information is high. Just to compare with the same geographical areas, 334 species are reported in a paper on medicinal plants (AE, [30]), which is representative of other territories, a figure higher than in other areas and not simply additive, since a high number of taxa are repeated in different areas, and 97 species were recorded in a work on ethnoveterinary in four out of the five territories here considered [31]. This supports the argument to consider the nonfood and non-medicinal folk plant uses as not secondary or residual at all. The number of use reports (hereinafter UR) confirms this, being also elevated (4137 in total, cf. Table 2 for their distribution in the geographical areas and Table 3 for its repartition for use categories).
To name the specific and infraspecific taxa the informants provided 1303 Catalan popular names, including whole plants and parts of plant, especially fruits and seeds, and elaborated products. This figure would be the equivalent to a mean of more than two names per plant, and roughly approaches the 5 % of the ca. 35,000 Catalan plant names (of folk and other provenances) recently collected [32], the quantity and diversity of names accounting too for the vitality of the knowledge of plants with these other uses. Additionally, the informants indicated 37 Spanish, four French and one Arabic names to refer to the plants reported. Table 3 presents the 14 categories (which are equally present for all territories in our database to avoid comparison) of non-food and non-medicinal uses in which we have classified all data collected. Some examples and comments on specific uses are provided in this and in other epigraphs of this paper (e.g., most reported taxa or persistence of uses), and the detail of all uses collected can be found in Table 1.

Use categories
The category "other informations" is a miscellaneous one to hold sparse knowledge not attributable to the established categories. This big group of information comprises 509 use reports from a total 4137, meaning ca. 12 % of all reports, but includes a very numerous and diverse cases, for which we have established the following subgrouping: ecological information, undesirable actions, purchased in commerce, harvesting and/or selling, excipient or adjuvant in medicinal or food preparations, product appreciations. We also attributed the category of other information to the cases in which the informants declared that they knew that a plant was useful, but they did not remember for what (use not remembered); we maintain this category (related, as the whole paper, to non-food and non-medicinal uses) as an evocation of knowledge that used to be solid, but has declined and is almost forgotten now.
Some big categories comprise several activities. Agrosilvopastoral: agricultural/horticultural, for pig slaughter, honey obtaining, for fishing, for hunting, forestry tools for agricultural practices, weeds. Artisanal: elaboration of canes, shoes, brooms, kitchen implements, musical instruments, baskets and similar objects, fibres, smoking paper, tobacco pipes and other instruments, as well as hide tanning. Domestic: household help, air fresheners, paint elaboration, help in sewing. Textile: fibre or cloth elaboration, textile padding, dyer. Timber: elaboration of furniture, boats and wheeled vehicles, obtention of building material.
With this, and irrespective of our grouping, made for the sake of concision, thus, the number of subcategories (including categories with no subcategories) would reach 46, showing a big coverage of different fields. The most common large use categories, in terms of number of use reports, are ornamental (646 use reports), agrosilvopastoral management (600), artisanal (534), and magic and religious beliefs and practices (421). For statistical purposes we used the main or big categories, since for many of the subcategories there are not enough use reports to allow a statistical treatment.                                         The first two of these categories have direct links with the rural society, which has been prevalent in all the studied territories until recent times and is still important, irrespective of the intervening socioeconomic changes. Plants used in agricultural and livestock raising tasks have been and many of them continue to be utilised (see the subheading on persistence of uses). Many local handicrafts and objects for domestic uses were and are elaborated. Many kinds of baskets (Fig. 2), spoons and other kitchen implements, often made with Buxus sempervirens L. wood, or broom ( Fig. 2; made with species such as Buxus sempervirens, Erica scoparia L., Mantisalca salmantica (L.) Briq. et Cavill. and Sarothamnus scoparius (L.) W.D.J.Koch -two of them with the specific epithet alluding to this object, suggesting the antiquity and relevance of this tradition-) were mentioned. The uses comprised in these two categories are also among the commonest in other European areas [11,13,14]. Moreover, handicraft elaboration has been reported as one of the most relevant uses in distant areas as well, e.g., [33]. Indeed, some uses belonging to other categories are also linked with rural activities. This is the case, among others, of using Datura stramonium L. as a repellent for moles, which can damage plant cultures.
The third group of uses is very common as well, since all human groups have influences of religious and/or magic beliefs. Protective plants (see the subheading on persistence of uses), or ritual ones (e.g., Laurus nobilis L., Olea europaea L. and Phoenix dactylifera L., which are blessed in Christian Easter feasts, Fig. 3) exemplify this group of uses.
Finally, the category of ornamental plants is also universal, both in rural and urban areas, both with living or cut plants, and both for indoor and outdoor spaces. This group of uses involves classical, large-scale cultivated plants (such as Rosa sp. cultivars), but a large number of wild plants as well, such as, among many others (see Table 1), Lunaria annua L. (Fig. 3), with the aerial parts with fruiting septa of which bouquets are prepared. Many ornamental plants also have other uses; amongst them, medicinal is not rare, and in some cases the medicinal application used to be important and has decreased, but the ornamental use persists (such as, for example, in Lilium candidum L.). Decorative uses are very dynamic. The ancient traditions in this field coexist with recently adopted ones, such as using Poinsettia pulcherrima (Willd.) Graham toghether with the classical Ruscus aculeatus L. for home ornamentation at Christmas (Fig. 4).  . All these families, except the last one, are big in terms of number of taxa and are importantly represented worldwide and, in particular, in the Mediterranean region, to which the territories considered belong. This would agree with the assessment that plant taxa common or well-represented in one area are more accessible to its inhabitants and, so, most likely used there [34]. Three of these families, Asteraceae, Lamiaceae and Rosaceae, are almost always dominant in ethnobotanical works conducted in the Catalan cultural area and in other western Mediterranean countries (see, for instance, [35] for a Catalan territory and [36,37] for non-Catalan areas, and references contained in these papers) even if those works are focused on food and medicinal plants and the present one on other uses. The coincidence is also important (four out of the five main families of the present paper) even with work conducted in several eastern Mediterranean areas [14]. In contrast, the family Oleaceae is not very numerous in taxa, but it reached a very high number of UR mostly due to the relevance and versatility of uses of Olea europaea (including, but not only, olive oil, utilised for many different purposes) in all Mediterranean territories. The family Poaceae is not included among the most reported in the above-quoted ethnobotanical works on food and medicinal plants, but is, again, a very large one and with some prominent plants in the kind of uses here studied. Arundo donax L. is particularly significant in this sense. This allochthonous plant, acclimated from ancient times in the areas studied, has many uses, mostly linked to agricultural practices (Fig. 3), in three of the territories (AE in Catalonia and both from BI), which account for many UR.
The five most cited species in the different regions studied are presented in Table 4. Again, Olea europaea is present in the top plants list, being the most reported one in the Balearic areas considered and in one of the Catalonian territories (altogether, and logically, in the most strict Mediterranean areas among those studied) for the reasons stated in the last paragraph. The coincidence of Buxus sempervirens as highly quoted in the three Catalonian territories responds, apart from its popularity due to the high quality of its wood, to the existence of Eurosiberian zones in these continental areas, and to its practical or total absence from Balearic ones. Conversely, Chamaerops humilis (Figs. 2 and 3), much more present in the Balearic areas considered, and scarce or inexistent in the Catalonian ones, is, not surprisingly, highly reported in the former. Most quoted taxa are quite different from those leading the lists of top plants for medicinal or food uses in the areas considered ( [28,38] and references therein), with the exception of Olea europaea, which also plays a relevant role in the mentioned fields.

Parts of plants
The use categories object of the present paper being very diverse, almost all plant parts (and the whole plants as well) are used. Stem (1156 UR; 27.94 %), aerial part -constituted either by all the aboveground part of the plant or by leaves and flowers together, with the stem or branch portions sustaining them-(785 UR; 18.98 %), flower (including inflorescence and flower, 337 UR; 8.15 %) and leaf (295 UR; 7.13 %) have been the most reported plant parts. Frequently, the whole plant is also used (869 UR; 21.01 %). Sometimes, the aerial part and the whole plant have constituted indistinguishable categories. The high number of use reports attributed to the stem is due to large and diverse kinds of artisanal uses, wood products and fuel.

Comparison between the territories studied
As stated when addressing the most recorded taxa, the territories studied share a language and culture, but differ in ecogeographical characteristics. For these comparative purposes we have put together both Balearic territories, since Formentera's dataset is not big enough to be taken into consideration.
Chi-square test showed there was an association between use categories and territories (χ 2 = 846.306, d.f. = 39, P < 0.0001). Particularly, the presence of continental and insular areas leads us to suppose some differences in ethnoflora applications, possibly due to differences both in flora and in traditions. Indeed, there is also a significant difference in the use categories between continental and insular territories (χ 2 = 485.037, d.f. = 13, P < 0.0001), confirming this geographical effect.
We present in Fig. 5 the degree of coincidence in plants used in the five regions considered. Whereas the number of coincident species among three territories ranges from 43 (Balearic Islands, Montseny and Ripollès) to 76 (Alt Empordà, Balearic Islands and Montseny), this decreases to 34 when we analyse the intersection of the four areas included in this study. In any case, we believe that the amount of plants used for non-medicinal and non-food aims in all areas is rather high. These plants with a larger geographical reach are usually cosmopolitan species used in daily life in the territories of Catalan culture, such as Fagus sylvatica L., Laurus nobilis, Malva sylvestris L., Olea europaea, Papaver rhoeas L., Ruscus aculeatus, and Spartium junceum L. (Table 1).

Reliability of uses recorded
As already stated, the uses here reported are divided in a large number of categories. Irrespective of this dispersion, which is logical, since we consider here all traditional plant uses apart from food and medicinal ones, we think it is necessary to evaluate the degree of reliability of the information provided by the interviewees on these uses. A first, simple approach to this is considering the frequency of uses (see Table 1 for plants and Table 3 for use categories). According to several authors [33,39], a use could be considered reliable if it is quoted by at least three independent informants. In most cases both the plants and the uses have been quoted by more (usually many more) than three informants. A finer approach is provided by the informant consensus factor (F IC ; [40]), defined as the number of UR minus the number of taxa divided by the number on UR minus 1. This index reflects the reliability of ethnobotanical information considering the coincidence of the informants in the same uses to be attributed to the same plants. The closer F IC is to its maximum value, 1, the more consistent -thus, the more reliable-are the folk plant uses considered in the area studied. The general F IC value in this study is 0.87 and those for the two big geographical areas concerned (Catalonia and Balearic Islands) are coincidental, 0.82. To our knowledge, this is the first, or one of the very rare times, that F IC is calculated for uses other than medicinal and food ones. The absolute values can be considered rather high. Comparatively, they are higher than those calculated for medicinal uses in two Mexican and one Indian areas (ranging from 0.75 to 0.79; [41][42][43]). This means that other uses in the territories here studied are slightly more coincidental than medicinal uses in places where folk use of medicinal plants is highly practiced and considered, suggesting a high consistency and reliability of the information collected. The F IC values here presented are very close (although in a few cases slightly lower) to those obtained for food and medicinal plant uses in the areas object of study ( [31,35], and references therein). This testifies for the robustness of the dataset collected, confirming the relevance of these other uses of plants for the human populations practicing them.

Persistence and consideration of non-food and non-medicinal folk plant uses
If indices such as F IC permit a quantitative assessment of the non-food and non-medicinal popular plant uses, the interviews performed with a big number of informants in the five studied areas allow us to qualitatively evaluate their current situation as well. Our aprioristic idea was that, in an industrialised society, these uses, most of them not directly linked to wellness and hardly related to rural life, would be residual and not much considered, at least in part due to the processes of acculturation and erosion of traditional knowledge. Nevertheless, once considered in detail the definitely high amount of information collected, we believe that these uses are (at least still) not so marginal. We contribute here some reflections on this subject with different possibilities for the uses considered, illustrated with a few examples, and  Table 1.
Undoubtedly, some of these uses have declined, in some cases nearly or completely until extinction. We can note in this category some artisanal works and most traditions linked to religious and/or magic beliefs. For instance galoshes (Fig. 4), for which the wood of several trees was employed, are no longer in use in agropastoral tasks (so, they are no longer fabricated), but the informants who used to employ them and those who used to elaborate them (one of our informants was one of the last artisans who elaborated galoshes in Catalonia, until 1980) precisely remember the details of their use and had often brought into the house some pieces as decorative elements with an added value. In the Catalan society, the same degree as in the Netherlands -where galoshes have become an identitary element, with, additionally, a big implication in merchandising and tradehas not been reached, but nowadays the few people who know how to fabricate them are often required in popular feasts to show off their former trade. Indeed, courses or workshops on these and other subjects related with traditional plant uses (e.g., dyeing) are frequently organised. Similarly, carpets elaborated with vegetal elements are no longer used in religious processions (simply because these processions do not exist currently), but in some localities in two of the areas studied (Alt Empordà, Montseny) the carpets continue to be prepared every year in the context of a popular feast (Fig. 4). In other cases, such as the elaboration of matrasses with Zea mays L. inflorescence bracts or that of sheets with Cannabis sativa L. fibres, the uses have been completely abandoned.
Even in some trades that are declining, a certain degree of vitality persists: the elaboration of musical instruments for the orchestra (named cobla) that plays typical Catalan dances (called sardana) and for other kind of traditional musical events, importantly involving Ziziphus jujuba Mill. (Fig. 4) continues to be alive, even if their artisans must have another profession to make a living.
Apart from these declining uses, some other persist almost to the same extent as always. These are uses linked to everyday life mostly in rural areas, such as those related to agricultural practices (in homegardens or elsewhere), e.g., tutoring some cultivated plants (Fig. 3). Another kind of folk plant knowledge to persist is that related to ludic aspects, including oral literature. People continue to play with plants and to use sayings and proverbs involving the vegetal world (even to inventing new ones). Additionally, some plant uses directly linked to commercial issues have also a high degree of persistence, such as those related to basketry (Fig. 1) or Christmas/New Year decoration (Fig. 4).
Finally, some popular traditions linked to plants are still in use, but have changed in some senses. As an example, some plants are hung in or near the doors of many rural houses (especially in mountain areas), as was commonly done since time immemorial, such as Carlina acanthifolia (Fig. 4). Nevertheless, no one believes nowadays (even if many people did a few decades ago) that these plants are protective for people and animals in the house. In this case, these plants now play a decorative role, with the associated interest that people know that this current use derives from a quite different ancient one. The basket elaboration mentioned in the last paragraph and similar activities, such as some related to textile, dyeing and handicraft issues, have also experienced, at least to some extent, this change. In past times, baskets, carpets, blankets, forks, spoons and other objects were elaborated with plant material simply for their use within the house, but now most such pieces produced are addressed to decorative and touristic purposes, comporting some commercial revenues.

Conclusions
The important number of species claimed to be used (552, with 4137 use reports) by the 769 informants interviewed in the territories studied for the purposes comprised in this paper show that popular knowledge on plants goes far beyond food and medicinal applications, which had been the most traditionally studied in ethnobotanical surveys, probably because they are the most apparent and the most preserved plant utilisations. This means that a large and diverse panoply of traditional uses, which are apparently secondary in our industrialised societies, such as examples as different as basket elaboration and oral literature, remains active and, when this is not so, appreciated and remembered by people.
To summarize, we believe that the data in this study show that a robust set of knowledge and practices in the field of non-food and non-medicinal plant uses persists in the European industrialised area studied, indicating that these utilisations of plants, which to date have been the object of scarce attention in ethnobotanical research, are relevant -we would say fully necessary-for a complete life, even in a modern society and even if they are not directly related to health issues. Additionally, and not forcibly negatively, although this means a reorientation in the tradition, some changes in popular uses (mostly those related to handicrafts) currently imply a certain complementary income for some people and may represent a potential for future commercial activities with economic significance in rural communities.
Further ethnobotanical studies in this currently still rather neglected field are encouraged in order to compile an important part of natural and cultural heritage not sufficiently considered up to now, and to assess what actions are needed to preserve this knowledge, particularly in cases of dangerously declining real current practice.