Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Morphological data and single- to low-copy nuclear DNA restriction enzyme site data were used to test subspecies circumscriptions of Solanum bulbocastanum and S. cardiophyllum. A prior chloroplast DNA analysis showed these species to be part of two main clades: 1. S. bulbocastanum subsp. bulbocastanum, S. bulbocastanum subsp. dolichophyllum, S. bulbocastanum subsp. partitum, S. cardiophyllum subsp. cardiophyllum and S. cardiophyllum subsp. lanceolatum, and 2. S. cardiophyllum subsp. ehrenbergii and other Mexican diploid species. The nuclear DNA and morphological data showed S. cardiophyllum subsp. ehrenbergii to be slightly distinguishable from the other subspecies of S. cardiophyllum, and do not support the distinction of subspecies within either species. These data add to a growing body of evidence that there are too many wild potato taxa recognized.

We investigated the differences between two trees species in total C, N and P concentrations in live leaves, literfall, and surface litter. The work was conducted on individuals remnant in pastures, in a tropical deciduous forest ecosystem on the coast of Jalisco, Mexico. The use of nutrients differed between the two species: Cordia elaeagnoides had higher P concentration in live leaves, litterfall and surface litter than Caesalpinia eriostachys, but the latter species had a higher P use-efficiency. In contrast, the amount of nutrients fluxed through litterfall varied among years, suggesting that the productivity of specific year determined the amount of nutrients returned to the soil. However, the magnitude of this effect can be depleted by the short residence time of organic matter and nutrients of surface litter associated to both species.

Tigridia potosina, a new species discovered in the Sierra de Álvarez, San Luis Potosí, Mexico, is described and illustrated. The new species belongs to subgenus Hydrotaenia and is morphologically similar to Tigridia multiflora (Herb.) Ravenna but is distinguished by the size and the color of tepals, and by the width of the floral cup. Also the new species may be confused, because of the flower color, with T. alpestris Molseed ssp. obtusa Molseed, but differs from that taxon in the form of tepals and in the larger style branches.

Two new species from the state of Morelos, Mexico, are described and illustrated, Malaxis ribana Espejo & López-Ferrari and Habenaria uncata R. Jiménez, L. Sánchez & García-Cruz. Both species were collected in the surroundings of the city of Cuernavaca.

The genus Viridantha Espejo (Bromeliaceae) with two sections and six species, all endemic to Mexico and previously treated as Tillandsia, is proposed as new. Viridantha is characterized by the stamens equal in length, flat filaments and subbasifixed anthers, 2 - 4 mm long; ligulate, free, dark green petals; distichous, protandrous flowers; long asymmetric, densely to very densely disposed scales, and simple-erect stigmas (type I, sensu Brown & Gilmartin).

The generic name Microepidendrum Brieger ex W. E. Higgins is validated, an epitype of Epidendrum subulatifolium A. Rich. et Gal. is selected, and a new combination Microepidendrum subulatifolium (A. Rich. et Gal.) W. E. Higgins is proposed. Other species included in Microepidendrum by Brieger are excluded from the group. A phylogeny of the subtribe Laeliinae is presented showing the genus Microepidendrum Brieger ex W. E. Higgins to be sister to all other genera in Laeliinae and not closely related to Epidendrum or Encyclia.

It is estimated that in Mexico the Euphorbiaceae are represented by 43 genera and 782 species. In addition, there are 32 infraspecific taxa: 8 subspecies and 24 varieties. A preliminary list of the taxa is provided. The most diverse genera are Euphorbia (241 spp., 31%), Croton (124 spp., 16%), Acalypha (108 spp., 14%), Jatropha (48 spp., 6%), and Phyllanthus (41 spp., 5%). Together, these represent 72% of the species present in Mexico. There is one endemic genus, Enriquebeltrania. It is estimated that 57% of the Mexican species are endemic to the country. Employing the concept of Megamexico, 78% of the species are endemic. There are ten introduced species and one introduced genus (Ricinus). Within the country, the family is most diverse along the Pacific and Atlantic slopes. At the level of genus, the Mexican Euphorbiaceae show a strong affinity with Central and South America. At the level of species, most Mexican Euphorbiaceae are endemic, but of the species that are not, 200 also occur in Central America, 138 in the United States, 85 in South America, and 55 in the Antilles. Almost no Mexican species are found naturally in the Old World. Despite their great systematic and floristic importance, an adequate understanding of the Mexican Euphorbiaceae is still lacking.

A new combination, Euphorbia trialata (Huft) V.W. Steinm., is made to accommodate Chamaesyce trialata Huft within Euphorbia. In addition, Adelia virgata Brandegee, a later homonym of Adelia virgata Poir. (= Flueggea tinctoria (L.) G.L. Webster), is given the new name Adelia brandegeei V.W. Steinm.

It is a possible to say, with certain doubt, that in the next decades, the structure of the educational system will be more right-angled, that in the next 20 years, the pressure to enter the system will diminish in elementary education and will increase in university level. The present time is a construction built by data and arguments, it is also susceptible to the interpretation of the past and it is possible to assume this connection as radically uncertain and weak, besides provisional and easy to review. This is all about making legitimate the ambiguity that in every look over present time, it will be intended to fit expectations and skepticism. For a concise reconstruction of the educational system, managed by government, known through indexes elaborated by specialists, the system delimitates education as something regulated by government: conforming basic conditions on both social and cultural equality. The educational system rises along with modern government; it was required that education would became relevant to life (public life) and to work. Knowledge has been the main resource and challenge of educational system. Refering to the system metaphors: individual formation, national unit, work market; the three of then coexist and compete in an unbalanced way. Educators believed they could find argument and access to the new world by forming individual. Freire and Piaget put all that as the mayor interest of the educational of moral subjects, that is why school is orientated towards the learning of contents related with culture, geography, history and not so much towards learning mechanisms and schemes necessary for democratic relations. Market has took over educational system, education is no longer conceived as the most important instrument against despotism but as a factor to economic development. The metaphor or market has gained terrain in the social imaginary. For many people, market has became a moral reference, understanding a good life as the access and distribution of goods; however, the educational system never solved the problem of being a citizen and professional formation system at the same time this, has caused a deep crisis. The 3 metaphores coexist and compete, the question is whether any of them will prevail or if it is possible a combination of them. Since the 90’s, the system is submitted to a new dogma, whose referent is the market, economic integrations and technological development. Its is a predicted a new world where knowledge will be the most important productive and social value; that way it is possible that knowledge will be the most important productive and social value; that way it is possible that knowledge society provide a new environment and rebuild the social legitimity of the educational system. Citizen formation walks through 3 paths: the moral, the reason and the legal. These should be the coordenates of a reflexive system of democracy learning. Such a system should take Piaget and Kohlberg´s structures referring to knowledge and moral conscience development.

The ceramic industry is a very important activity in several municipalities of the state of Guanajuato, where a significant and constant demand is kept for clay as raw material to formulate pastes used in the manufacturing of utilitarian and ornamental ceramic products. Traditionally, there have existed evidences about important clay deposits in the state of Guanajuato with suitable ceramic properties, which have not been completely characterized or quantified. Thus, considering the relevance of this raw materials to the ceramic industry in the region, as well as the difficulties to dispose of ceramic commercial materials with high and homogeneous quality at a low cost, the Centro de Investigaciones en Química Inorgánica and the Dirección de Fomento Minero del Estado de Guanajuato established a collaborating project focused on the study of the selected clay deposits and taking into account the following aspects: clay characterization, evaluation of the ceramic properties and calculation of the existing reserves. In this paper the results of the chemical and mineralogical characterization of the clays in the selected zone samples are presented. The results were reviewed with respect to the obtained values in the characterization of the commercial pastes ordinarily used by the potters in order to establish an initial estimation about the real potential of the clay deposits studied.