Medicinal plants in the southern region of the State of Nuevo León, México.

Background: Although the flora of the State of Nuevo León is well known, there are few records of ethnobotancial information. An ethnobotanical study was undertaken in order to know the medicinal plants used by people living at the scrublands and oak-pine forest areas in the southern Nuevo León. Collection of plants specimens and interviews were carried out among the people of the municipalities of Aramberri, Galeana, and Zaragoza. Since former studies in the region are scarce, the aim of this work was to record the medicinal species and their uses in the scrublands and oak-pine forest areas, of southern Nuevo León, Mexico, and also to know if there are differences in the number of species and number of uses knowledge by people.

Methods: Field work was carried out over a 2 years period; useful plants were collected and a total of 105 people from 46 different villages were interviewed. A database was compiled using data collected by means of semi structured interviews. The data were analyzed by means of non-parametric statistics, using goodness-of-fit test (Chi-squared) (number of species known by people of each municipality, number of uses known by people of each municipality), Chi-squared modified to incorporate the Yates Correction (number of species known by people living at scrublands and oak-pine forest); the Kruskall-Wallis test (number of species known by women and men of the three municipalities), and the Spearman's rank correlation coefficient (age and number of species known, and age and number of uses).

Results: A total of 163 medicinal plant species were recorded in the study area, comprising 108 wild and 55 cultivated plants. A total of 117 species were recorded in the oak-pine forest, and 111 in the scrublands area, a total of 68 were recorded in both areas; 68 medicinal species are used in all three municipalities, 40 wild and 28 cultivated. We documented 235 different medicinal uses. The most common plant parts used for medicinal purposes were found to be leaves (123 species), stems (55), fruits (28), roots (17), and bark (14). No differences were noted in the number of medicinal plant species identified among people, but differences were significant in their knowledge with respect to the number of uses among people of the three municipalities studied; people from both, scrublands and oak-pine forest know similar number of species and number of uses. Men and women of the three different municipalities knew statistically the same number of species and number of uses. There was no correlation between resident's age and number of species known and resident's age and number of uses either in Galeana or in Aramberri, but, there was high correlation among these variables in Zaragoza.

Conclusion: In southern Nuevo León people use at least 5% of the total State flora as medicinal plants, and most of these species are included in few plant families. Most of medicinal species are wild and indigenous to the region. The two most important major plant communities, scrublands and oak-pine forest provide almost the same number of medicinal species. A third of the medicinal flora recorded are used in all three municipalities, most of them are wild. Leaves, stems and fruits are the plant parts most commonly used for healing, and boiling is the most common method used for this purpose. Men and women from the three municipalities are familiar with nearly the same number of species; however, their knowledge of the number of uses varies significantly. In Galeana and Aramberri there was no correlation between a person's age and number of species recognized, however, in Zaragoza, there existed a high correlation between these two factors.