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Question: Understanding the specific distribution patterns of vascular plants on different spatial scales is central in ecology and conservation. We evaluate the distribution patterns of five plant life forms (climbers, epiphytes, herbs, shrubs, and trees) along the elevation gradient and geographic space of a mountain system, analyzing climate, topography, and human disturbance to explain variation in the richness of each life form, and determine the contribution of each life form to total richness along the elevation gradient. Location: Sierra Madre of Chiapas, southeastern Mexico. Methods: We used linear models to evaluate the elevational pattern of richness for each life form, as well as total richness, and analyzed the effects of climate (water–energy dynamics, thermal range), topography (topographic heterogeneity), and disturbance (Human Influence Index) on variation in total richness as well as of each life form using Generalized Linear Models (GLM). We used Non‐Metric Multidimensional (Distance) Scaling to determine variation in species composition along the elevation gradient. Finally, the contribution of each life form to total richness was evaluated using GLM. Results: We recorded 235 families, 1,439 genera, and 5,196 species. Total richness and the richness of each life form increased with increasing elevation. GLM explained a high proportion of the variation in the richness of each life form (34.3% for total richness; climbers 17.2%, epiphytes 44.9%, herbs 20.4%, shrubs 33.5%, and trees 24.9%). The proportion of richness of herbs and trees to total richness decreased, and the proportion of shrubs, epiphytes, and climbers increased with elevation. Climate largely determined species richness for all life forms, whereas disturbance was significant only for epiphyte richness. Conclusions: Results suggest that mechanisms driven by climatic variables (especially thermal range) contribute to maintaining the richness of each life form. However, human disturbance modifies distribution patterns and leads to a decrease in epiphyte richness. The differential contribution of each life form to total richness along the elevation gradient presents a challenge for designing conservation strategies applicable to all plant groups. [ABSTRACT FROM AUTHOR]

Crops that offer multiple types of value, for example, in terms of economy, culture, and health, frequently lack information on the basic ecological interactions that play a significant role in their persistence. Chayote (Sechium edule, Cucurbitaceae), a widespread squash valued for its nutritious fruit, is one example. We aimed at describing the assemblage of flower visitors to this crop at 2400 m where stingless bees, reported as the main pollinators, are naturally absent. We implemented flower exclusions, performed field observations, and inspection of pollen loads of captured visitors to be able to draw distinctions between primary and secondary pollinators. We recorded a total of 60 species or morphospecies of insects visiting the flowers. Bees, wasps, and flies, present in all sites and consistently carrying abundant pollen, are the main pollinators of S. edule at high altitudes. Our study adds to the building evidence of the fundamental role that native bees and wasps play as crop pollinators in subsistence farming. Basic ecological knowledge is essential to inform agricultural management policies and to foresee preventable food scarcity problems, especially in view of climate change scenarios that predict drastic alterations in plant geographical distributions. [ABSTRACT FROM AUTHOR]

Understanding how species respond to climate change is critical for implementing conservation strategies. Objective: We explain through potential distributions and changes in altitudinal variation, the possible impacts of climate change in an endangered micro-endemic rodent of Mexico with narrow altitudinal range, Heteromys nelsoni and a rodent with a wide distributional and altitudinal range, Heteromys goldmani. Methods: We obtained historical and current records of both Heteromys species. Potential distribution models were generated using Maxent, including altitudes for each species and bioclimatic layers. We determined the Extent of Occurrence and Area of Occupancy for H. nelsoni according to the criteria of the IUCN in order to generate information about its risk status. Results: The altitude is not a variable that determines a shift in the distribution caused by climate change. In contrast, the temperature and precipitation are important for the potential distribution of both Heteromys species. The future changes in climatic conditions could reduce the area of suitable habitat for both species. Conclusions: The distribution surface is not greater than 33.44 km2 for H. nelsoni. Therefore, is urgent to re-evaluate their conservation status by the IUCN, mainly in its B criterion, and to take specific actions for their conservation. We suggest the creation of a terrestrial protected area. [ABSTRACT FROM AUTHOR]

Evidence is presented about the presence of Phaseolus microcarpus in Costa Rica, while it was previously reported northwards in other Central American countries and Mexico. Fourteen populations are currently known, four from the Peninsula of Nicoya, and ten are in the tropical dry forest of the mainland of this country. [ABSTRACT FROM AUTHOR]

Se presenta información acerca de Gochnatieae, un subfamilia de la familia del aster, incluyendo su distribución geográfica en México y sus diferentes especies, incluyendo Nahuatlea hypoleuca y Nahuatlea magna.

Environmental heterogeneity of Belize and southern Mexico savannahs as well as their geographical location suggest that these plant communities share floristic elements, making them conducive to a phytogeographical analysis. The aim of this study was to analyse the floristic affinities of nine savannahs of Belize and southern Mexico and to explain the similarities and differences amongst them. A binary data matrix containing 915 species was built based on the authors' own collections and on nine floristic lists already published. A second data matrix, consisting of 113 species representing trees, was also used since most literature on neotropical savannahs has focused on this life form. In addition, the ten most species-rich families as well as the characteristic species present in more than five savannahs were analysed. Floristic similarities were calculated using the Jaccard index. Dendrograms obtained in both types of analysis showed clusters with low similarity values, corresponding to geographic locations formed by the savannahs of Belize-Tabasco and the Yucatan Peninsula. The floristic affinities of the savannahs may be explained in terms of heterogeneity in climate and physiography. The Yucatan Peninsula and Belize-Tabasco groups have differences in climate type and the amount of rainfall. In addition, the Yucatan Peninsula savannahs are established at the bottom of karstic valleys, while the Belize and Tabasco savannahs develop on extensive flatlands. The savannahs of Oaxaca have the same climate type and amount of rainfall as those of the Yucatan Peninsula but they are distributed along peaks and the slopes of shale hills. Fabaceae and Poaceae mainly dominated the local floras with 121 and 116 species each; remarkably, Melastomataceae was absent in the Yucatan Peninsula and Oaxaca. Nine species occurred in five to seven savannahs, confirming that they are widespread in both Belize and southern Mexico, and the Neotropics. Geographic location and floristic affinities of the nine savannahs support, to some extent, three different biogeographic provinces. [ABSTRACT FROM AUTHOR]

Forest fires are a cause of global concern, which requires generating knowledge on their spatial behavior. By hypothesizing that the spatial pattern of forest fires across Mexico is randomly distributed, this study aimed at making an analysis of the distribution of forest fires (2005-2015) using remote sensing information and field data collected by CONAFOR (National Forest Commission) and MODIS (Moderate-Resolution Imaging Spectroradiometer). The study compared both sources of information through the G-statistic test that identified clustering patterns. The "hot spots" analysis identified clustered areas with significant values in both data sources. These zones were extended through Sierra Madre Occidental, Península de Yucatán, northern Sierra Madre Oriental and Península de Baja California. The highly coincidental clusters were found in the central-western region along the Eje Neovolcánico, as well as in a small part of Sierra Madre del Sur. The analysis of spatial correlation determined that both sources of information complement each other, enhancing their scope. It is concluded that forest fires in Mexico follow a spatial clustering trend. [ABSTRACT FROM AUTHOR]

Jatropha curcas is a native Mexican plant, distributed in the forests of coastal regions; it has shown potential for the production of biofuel, and its raw protein can be used as animal feed. Nevertheless, its current varieties have low yield and production variability, as it is in domestication period. The knowledge of the pollen grains is fundamental for studies of Jatropha reproductive biology and breeding for genetic improvement to generate new hybrids and improve fruit and seed yield. This study compared pollen morphology of four Jatropha species, which include two varieties of J. curcas (one toxic from India and one non-toxic from Mexico), and two varieties of wild J. cinerea (Sinaloa and Baja California Sur); additionally, pollen was collected from wild J. platyphylla (Sinaloa) and J. vernicosa (Baja California Sur) to characterize them palynologically. We used a scanning electron microscope to describe the size and shape of pollen grains. Pollen grains were observed spheroidal. The diameter of the varieties of toxic and non-toxic J. curcas and that of J. platyphylla were 58 ± 2.3, 54 ± 1.7, and 51 ± 2.4 μm, respectively; the number of clavae was 84 ± 10, 108 ± 15, and 180 ± 15.5, respectively. Pollen grains of J. cinerea (Sinaloa) had a diameter of 50 ± 1.7 μm and 220 ± 14 clavae by area; J. cinerea (Baja California Sur) had a diameter of 45 ± 1.9 μm and 195 ± 14.7 clavae. Pollen grains of J. vernicosa had a diameter of 46 ± 2.1 μm and 231 ± 25.6 clavae. The ornamentation of the exine showed clava with capita gemma shaped for varieties of J. curcas species and clavum shaped for J. platyphylla, J. cinerea and J. vernicosa species. The studied varieties have a cross-linked endexine and ectexine intectate. Luminal bacules were observed in the reticular space of J. curcas varieties while none were present in the varieties of J. cinerea, J. platyphylla, and J. vernicosa. [ABSTRACT FROM AUTHOR]

Cascabela is a Neotropical genus of Apocynaceae with six species: C. balsaensis, C. gaumeri, C. ovata, C. pinifolia, C. thevetia and C. thevetioides. Its taxonomic history has long been a subject of controversy, especially due to its circumscription as a genus closely related to Thevetia. In this work, we revised the taxonomy of Cascabela for Mexico and provide detailed descriptions and illustrations. We also applied species distribution models and geographical information tools to evaluate chorological aspects of the six species occurring in Mexico and provide a conservation category. According to our results, Cascabela has a typical tropical distribution within Mexico, and the Balsas basin was identified as an area of diversity and endemism for the genus. The species C. ovata and C. thevetia have the broadest distribution ranges, and we assigned them the category of least concern. We suggest that the restricted, endemic species C. balsaensis, C. pinifolia and C. thevetioides be considered for protection. The genus was corroborated as an element of deciduous forest, and its cultural importance is highlighted. [ABSTRACT FROM AUTHOR]

Stephaniellaceae (R.M. Schust.) R.M. Schust. is a small family that occurs in the high elevations of the Americas, from Mexico to northern South America and South Africa. This taxonomic revision is based on the examination of herbarium specimens from various parts of its range, and field work in Mexican localities. The taxonomic treatment provides a re-description and illustration of the family, its genera and species, and a taxonomic key based on gametophytic characters. Five species in two genera ( Stephaniella and Stephaniellidium) are recognized. Stephaniella is characterized by hyaline leaves, abundant paraphyllia, and sporophyte developed within the perianth. Stephaniellidium is characterized by chlorophyllose leaves, scarce paraphyllia, and sporophyte developed within a marsupium. [ABSTRACT FROM AUTHOR]

The floristic inventory of the Sierra de Quila Natural Reserve, in western Mexico, resulted in the discovery of Polianthes quilae ( Polianthes subgen. Bravoa). The novelty is related to P. cernua and P. geminiflora var. clivicola but is distinguished by the erect lanceolate leaves, glauous inflorescence with 4-21 floral nodes, 0.9-2.1 cm long pedicels, tubular-ventricose and bicolorous perigone with ascending lobes, and filament insertion site 3-5 mm above ovary apex. Data on geographic distribution and ecology, phenology, and conservation status are presented. Lastly, a key to all species of Polianthes is provided. [ABSTRACT FROM AUTHOR]

Wild specimens of Vanilla planifolia represent a vital part of this resource primary gene pool, and some plants have only been reported in Oaxaca, Mexico. For this reason, we studied its geographical distribution within the state, to locate and describe the ecological characteristics of the areas where they have been found, in order to identify potential areas of establishment. The method comprised four stages: 1) the creation of a database with herbarium records, 2) the construction of the potential distribution based on historical herbarium records for the species, using the model of maximum entropy (MaxEnt) and 22 bioclimatic variables as predictors; 3) an in situ systematic search of individuals, based on herbarium records and areas of potential distribution in 24 municipalities, to determine the habitat current situation and distribution; 4) the description of the environmental factors of potential ecological niches generated by MaxEnt. A review of herbarium collections revealed a total of 18 records of V. planifolia between 1939 and 1998. The systematic search located 28 plants distributed in 12 sites in 95 364 Km2. The most important variables that determined the model of vanilla potential distribution were: precipitation in the rainy season (61.9 %), soil moisture regime (23.4 %) and precipitation during the four months of highest rainfall (8.1 %). The species potential habitat was found to be distributed in four zones: wet tropics of the Gulf of Mexico, humid temperate, humid tropical, and humid temperate in the Pacific. Precipitation oscillated within the annual ranges of 2 500 to 4 000 mm, with summer rains, and winter precipitation as 5 to 10 % of the total. The moisture regime and predominating climate were udic type I (330 to 365 days of moisture) and hot humid (Am/A(C) m). The plants were located at altitudes of 200 to 1 190 masl, on rough hillsides that generally make up the foothills of mountain systems, with altitudes of 1 300 to 2 500 masl. In natural conditions, distribution of the species is not limited to high evergreen forests, since it was also found in mountain mesophyll and tropical evergreen forests. The location of new specimens of V. planifolia in its wild condition reduces the potential distribution area by 66 %. This area is fragmented into three geographically separated areas. Habitat reduction was due to the increased number of located plants that define the environmental conditions into a more accurate level. Conservation actions can thus be designed and implemented, focusing on more specific areas within the state of Oaxaca, Mexico. [ABSTRACT FROM AUTHOR]

Linnaeoideae is a small subfamily of erect or creeping shrubs to small trees in Caprifoliaceae that exhibits a wide disjunct distribution in Eurasia, North America and Mexico. Most taxa of the subfamily occur in eastern Asia and Mexico but the monospecific genus Linnaea has a circumboreal to north temperate distribution. In this study, we conducted phylogenetic and biogeographic analyses for Linnaeoideae and its close relatives based on sequences of the nuclear ribosomal ITS and nine plastid (rbcL, trnS-G, matK, trnL-F, ndhA, trnD-psbM, petB-D, trnL-rpl32 and trnH-psbA) markers. Our results support that Linnaeoideae is monophyletic, consisting of four eastern Asian lineages (Abelia, Diabelia, Dipelta and Kolkwitzia), the Mexican Vesalea, and Linnaea. The Mexican Vesalea was formerly placed in Abelia, but it did not form a clade with the eastern Asian Abelia; instead Vesalea and Linnaea are sisters. The divergence time between the eastern Asian lineages and the Mexican Vesalea plus the Linnaea clade was dated to be 50.86 Ma, with a 95% highest posterior density of 42.8 Ma (middle Eocene) to 60.19 Ma (early Paleocene) using the Bayesian relaxed clock estimation. Reconstructed ancestral areas indicated that the common ancestor of Linnaea plus Vesalea may have been widespread in eastern Asia and Mexico or originated in eastern Asia during the Eocene and likely migrated across continents in the Northern Hemisphere via the North Atlantic Land Bridges or the Bering Land Bridge. The Qinling Mountains of eastern Asia are the modern-day center of diversity of Kolkwitzia-Dipelta-Diabelia clade. The Diabeliaclade became highly diversified in Japan and eastern China. Populations of Diabelia serrata in Japan and eastern China were found to be genetically identical in this study, suggesting a recent disjunction across the East China Sea, following the last glacial event. [ABSTRACT FROM AUTHOR]

El artículo discurre sobre la distribución, el origen y los usos ornamentales de la planta mexicana el maguey. El autor comenta sobre los magueyes en Oaxaca y Puebla y describe otros usos como usos textiles, medicinales y para hacer la bebida alcohólica pulque. El artículo provee varias imágenes de la planta.

In the arid and semiarid region of Mexico, data on three native grasses growing in diverse ecological environments--Muhlenbergia peruviana (P. Beauv.) Steud., in temperate forests; Bouteloua gracilis (Kunth) Lag. ex Griffiths, in grasslands; Muhlenbergia porteri Scribn. ex Beal, in xeric regions; and one introduced nonnative species, Melinis repens (Willd.) Zizka (Zizka rose Natal grass)--were used in our essay analyzing their potential distribution, based on climatic factors. We took presence-only data applied to the Bioclim algorithm included in the Diva-GIS program. Using database bioclimatic WorldClim-Global Climate Data allowed us to make predictions of the distribution, and to determine the climatic characteristics that each species needs to grow. It generated a potential distribution of the four species under study, concluding that this method can be applied to other grass species from this geographic area in order to improve: a) knowledge of the actual distribution of species in their natural environment, b) knowledge related to biodiversity, and c) to create an indicator to support decisions related to conservation and management of grasses in Mexico. We concluded that possibly climatic requirements prevent the expansion of the introduced species (Zizka rose, Natal grass). [ABSTRACT FROM AUTHOR]

An area of endemism is defined by the spatial congruence among two or more species with distributions that are limited by barriers. In this study, we explored and discussed the use of the network analysis method (NAM) and neighbor-joining (NJ) to analyze the areas of endemism of Quercus sect. Lobatae (red oak species) in Mexico and Central America. We compared the NAM and NJ with other methods commonly used in biogeographic studies to show the advantages of these new approaches and to identify the shortcomings of other approaches. The NAM used in this study is based on notions of centrality measures, such as betweenness. We incorporated the strength of the ties within the internal networks through p-cores and aggregate constraints in iterative analyses. The NAM based on betweenness is ideal for recognizing completely allopatric areas of endemism. The iterative NAMs increase the number of possible areas of endemism because they minimize the effect of minimal overlap, and the p-core is efficient at identifying the closest relationships among species in the cases in which betweenness is not informative. The number of areas of endemism increases when the sympatry matrix minimizes the dispersal effect and the sample effort is maximized, allowing the identification of the greatest number of these areas. The NJ method supports the idea that areas diverge among themselves in a differential way; the long branches correspond to zones with high speciation rates and complex histories (biotic and tectonic), and the short branches correspond to zones with low speciation rates and simple histories. In a classification scheme, NJ was capable of identifying the areas that are considered biotically complex because of their high speciation rates. The results obtained with the NAM and NJ showed that the physiographic regions of Mexico are not natural units and that many of them are composed of at least two different biotic components. [ABSTRACT FROM AUTHOR]

The Jurassic flora of Mexico represents a key element for the knowledge of the paleoflora on the western margin of equatorial Pangea because of its abundance and diversity. Bennettitales were the dominant group and are represented by leaves and reproductive organs in Jurassic outcrops from southern Mexico. This group has been historically recorded in seven lithostratigraphic units in southern Mexico in a range from the Toarcian to the Callovian. These reports have focused on morphological and taxonomical aspects for the obtention of paleofloristic listings by locality but do not provide environmental data or have any impact on biostratigraphic or phytogeographic analyses. The highest number of localities in Mexico has been reported in the state of Oaxaca, where plant fossils are more abundant and better preserved in comparison with localities of Guerrero, Puebla, Veracruz, and Hidalgo states. Therefore, in order to reinforce the paleofloristic knowledge of southern Mexico, the present study documents the diversity of Bennettitales in northwestern Oaxaca region, which is composed of 11 fossil-genera and 41 fossil-taxa, included 30 valid species and 11 species that need taxonomic revision. We provide the description of a new species, Williamsonia sanjuanensis sp. nov., new findings of Williamsonia nathorstii, and the first record of Bennetticarpus for southern Mexico. We also describe fossiliferous outcrops of the Zorrillo and Zorrillo/Taberna undifferentiated formations and propose their sedimentary environments. In addition, we provide a proposal of one biozone based on Bennettitales. Finally, we recognize six spatio-temporal distribution patterns for this plant group in northwestern Oaxaca. These new data add to a growing set of information on the Jurassic flora of Mexico and allow to substantiate the paleobotanic importance of southern Mexico within the region of North America. • A new species of Williamsonia is described from the southern Mexico. • So far, 41 taxa of Bennettitales have been reported in southern Mexico. • We provide the first proposal of a biozone based on Bennettitales for the northwestern Oaxaca. • We recognize six spatio-temporal distribution patterns of Bennettitales in northwestern Oaxaca. [ABSTRACT FROM AUTHOR]

The geographic and host distributions of Arceuthobium hondurense and A. nigrum (Viscaceae) in southern Mexico and Central America have remained unclear due to difficulties in their identification. This study was conducted to clarify the morphology, phenology, distribution, and host affinities of these dwarf mistletoes. Morphological measurements were made for these species across their geographic distributions and nr ITS sequences were generated and compared from selected populations in Mexico. Although subtle, interspecific differences in plant morphology were found, A. hondurense and A. nigrum can be differentiated by the dimensions of their staminate spikes, staminate flowers, and fruits. Our data also indicated that A. hondurense and A. nigrum were not sympatric. Arceuthobium hondurense is distributed from northern Nicaragua to northern Oaxaca, Mexico and A. nigrum is distributed from Veracruz to northern Durango. Although A. hondurense and A. nigrum flowered in the fall, A. hondurense consistently peaked in September and A. nigrum peaked in October, extending into January in central Mexico. A spring flowering period reported previously for A. nigrum was not observed. Additional information on the host distribution and molecular differences of these dwarf mistletoes is also presented. [ABSTRACT FROM AUTHOR]

New localities of geographic distribution for two grasses of Mexico are presented. Muhlenbergia filiculmis Vasey, a species known only in the West of United States is registered for the first time in Mexico. So is the distribution of Distichlis eludens (Soderstr. & H.F. Decker) H.L. Bell & Columbus, is expanded into a regional level, since it has been recently collected in Zacatecas, Mexico. [ABSTRACT FROM AUTHOR]

To better understand the potential distribution of Taxus globosa Schlecht., we used a conifer species with restricted distribution, listed on the NOM-059-SEMARN AT-2010, a modeling distribution procedure of maximum entropy or MaxEnt, based on 40 occurrences of field records and 39 REMIB -CONABIO records. Two different scenarios of geographical and environmental coverages--climatic and topographic--were proved statistically. The BIOCLIM variables scenario with topography data show a more accurate model in the range of 0.9 to 1.0 probability with a 55% coincidence; it was statistically significant at (AUC=0.985). Slope variable indicates an environmental variable with more influence in potential modeling, followed by Bio14 (Precipitation of Driest Month). In agreement with the MaxEnt analysis with 19 BIOCLIM and 3 topographic variables, the main plant communities in the modeling area (where Taxus globosa is distributed in Mexico) are pine-oak forest, oak-pine forest, pine forest, and cloud mesic forest. Taxus globosa is potentially distributed in Hidalgo, Nuevo León, Puebla, Tamaulipas, and Veracruz. [ABSTRACT FROM AUTHOR]

Among the many explanations for the large biological diversity of Mexico is that it is the result of the contact between the Nearctic and Neotropical biotas; however, this contact-related explanation is not fully satisfactory and needs further examination in the light of historical biogeography. We offer newer insights into this issue by examining the history of the flora and the vegetation heterogeneity of the seasonally dry tropics of this country. Several environmental criteria can be used to define the seasonally dry tropical regions, but setting their precise geographical boundaries is not always straightforward. This is largely due to the large vegetation heterogeneity of this region, within which the tropical dry forest (TDF) is prominent. The origin of the TDF flora can be traced back at least as far as 20 million years before present and seems to be associated with the Tertiary North American flora. Available evidence does not support a South American origin of the TDF flora. Similarly, the separation of the TDF and the hot North American desert floras into two different bio-geographical realms is not warranted. The history of the seasonally dry tropical flora of Mexico strongly suggests that this bio-geographical dichotomy should be replaced by the recognition of the existence of a Pan-American Realm. [ABSTRACT FROM AUTHOR]

A review of the information on the richness and distribution of the Mexican aquatic and wetland (herbaceous) monocots, is presented, for the purpose of contributing to a better understanding of the flora distributed in the wetlands of the national territory. Three hundred eighty one species (392 taxa) belonging to 104 genera and 28 families, considered as strict aquatics or wetland plants, were registered; as well as 114 tolerant or facultative hydrophytes of lacustrine and pond habitats. Half of the 28 families correspond to taxa considered by most botanists as terrestrial, but they represent a large component of the Mexican aquatic flora (71% of the genera and 75% of the species). The endemics make up 14% of the monocots. Their presence throughout a great diversity of habitats and its representation in several vegetation types and communities, make them one on the most diverse ecological and geographical components in the American continent. About 46% of the species belong to meridional elements, while 25% correspond to boreal one; while the Mexican element (13.9%) is equivalent to the sum of the cosmopolitan and introduced species. [ABSTRACT FROM AUTHOR]

Hypothetically, the alpine and high elevation moss flora reached central Mexico by migration from northern latitudes following the western mountain ranges. Study of 774 specimens belonging to eighteen species of Grimmia identified four patterns of distribution in Mexico: species restricted to the Neovolcanic Belt, those mainly distributed in the northwestern states, widely distributed taxa, and endemic species. Track analysis showed that the generic distribution indeed followed the western mountains. Modeling was introduced to determine the potential ranges for most Mexican species of Grimmia and review the migration hypothesis. The resulting potential distribution maps using maximum entropy show that several species have discontinuous ranges in the northwestern states. Other taxa are restricted to the Neovolcanic Belt, and still others extend their potential distribution to stations in southern Mexico and Guatemala. Although the original hypothesis proposed that the high altitude moss flora was derived from temperate North America may still be acceptable, the South American distribution of various Species indicate that migration may have also proceeded from the south. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la familia de plantas herbáceas Typhaceae y especies de su género Typha. Para cada especie considerada, incluyendo T. domingensis, T. latifolia y T. angustifolia se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

The aim of this paper is to familiarize the reader with two alcoholic spirits deeply rooted in the rural culture of northern Mexico, as well as Agave angustifolia, known as "agave (or mescal) bacanora" in Sonora; and a group of species in the genus Dasylirion, known in Mexico as "sotols", and as "desert spoon" in the USA. Both share multiple morphological, physiological and ecological traits, which allow them to thrive in their arid environs. It also points out aspects unique to the two designations of origin that protect the elaboration of these distilled spirits, both formulated near the beginning of this century, as well as the sets of regulations specifying the standards for processing. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la familia de plantas herbáceas Phrymaceae y especies de su género Mimulus. Para cada especie considerada, incluyendo M. coulteri, M. pallens y M. minimus se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

El artículo enfoca en la familia de plantas Scrophulariaceae y sus géneros, entre ellos Capraria, Limosella y Verbascum. Para cada género y especie considerada, incluyendo Capraria biflora, Limosella aquatica y Verbascum virgatum se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

The article discusses a study which described new species of Urochloa (U.) from Western Mexico, including U. olivacea and U. pauciflora. Particular focus is given to the characters of Urochloa and Brachiaria. It notes that U. olivacea is an annual plant rooting at the lower nodes. Its sheaths are also shorter or longer than the internodes. Whereas, U. pauciflora is an annual plant with shorter sheats and exposed nodes. Also included are data on distribution, phenology and etymology.

El artículo enfoca en la familia de plantas Celastraceae y sus géneros representados en México incluyendo Celastrus, Pristimera y Acanthothamnus. Para cada género y especie, incluyendo las especies Acanthothamnus aphyllus, Celastrus pringlei y Crossopetalum uragoga se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

El artículo enfoca en la familia de arbustos hemiparásitos Viscaceae y sus géneros Arceuthobium y Phoradendron. Para cada una de sus géneros y especies se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

El artículo enfoca en la familia de plantas herbáceas Poaceae y su subfamilia Panicoideae que incluye la tribu Centotheceae. Para esa familia, subfamilia y tribu se indican las características morfológicas y anatómicas, se describe su distribución geográfica y se discurre sobre su presencia en la región de Veracruz, México.

Eleven populations of Taxus globosa were located and evaluated along of the Sierra Madre Oriental in the States of Nuevo Leon and Tamaulipas, Mexico. A complete inventory of the individuals in all Taxus globosa populations was recorded; data of height, diameter, canopy cover and density were also evaluated. The population data were organized in databases on rank classes into six height categories, seven canopies cover categories and seven diameter categories. A χ² test indicates that all the populations showed a normal distribution. The canopy cover and diameter variables showed higher values in correlation analysis (r = 0.9). The population curve tendency on height, canopy cover and diameter shows that isolated or inaccessible populations of Taxus globosa Las Tinajas, Julilo and La Camotera are the populations with more young individuals than the rest of the northeastern populations. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la familia botánica Dipentodontaceae y su género Perrottetia. Se describe la especia Perrottetia ovata, indicando sus características morfológicas y anatómicas. Se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

El artículo enfoca en el género de plantas herbáceas o subleñosas Panicum y su familia Poaceae, la cual incluye más que 450 especies. Para ese género y familia se indican las características morfológicas y anatómicas, se describe su distribución geográfica y se discurre sobre su presencia en la región de Veracruz, México.

The pedregal of Arócutin, with a surface area of approximately 31 km², is located in the Lake Pátzcuaro basin, in the northern portion of the Mexican state of Michoacán. This region belongs to the Trans-Mexican Volcanic Belt physiographic province. The vegetation found is an oak forest in different stages of succesion, intermixed with elements of tropical deciduous forest. The structure and floristic composition of each association is described. Intense botanical exploration for a period of two years resulted in the collection of 407 species of vascular plants, belonging to 262 genera and 96 families; these represent 38.76% of the total number of species in the Lake Patzcuaro basin. The most diverse families are: Compositae with 60 species, Leguminosae with 27, Labiatae with 19, and Gramineae with 18. Comparing the floristic list of the pedregal of Arócutin with those of three other outcrops of basaltic rocks along the Trans-Mexican Volcanic Belt, using the Sörensen similarity index, we found that the Arócutin and Huaniqueo pedregals are the most closely related, both at generic arid specific level. This is followed by the pedregal of San Ángel in Mexico City and finally the pedregal of Chichinautzin, Morelos. Additionally, traditional uses of some plants are recorded. [ABSTRACT FROM AUTHOR]

The pedregal of Arocutin, with a surface area of approximately 31 km², is located in the Lake Patzcuaro basin, in the northern portion of the Mexican state of Michoacan. This region belongs to the Trans-Mexican Volcanic Belt physiographic province. The vegetation found is an oak forest in different stages of succesion, intermixed with elements of tropical deciduous forest. The structure and floristic composition of each association is described. Intense botanical exploration for a period of two years resulted in the collection of 407 species of vascular plants, belonging to 262 genera and 96 families; these represent 38.76% of the total number of species in the Lake Patzcuaro basin. The most diverse families are: Compositae with 60 species, Leguminosae with 27, La-biatae with 19, and Gramineae with 18. Comparing the floristic list of the pedregal of Arocutin with those of three other outcrops of basaltic rocks along the Trans-Mexican Volcanic Belt, using the Sbren-sen similarity index, we found that the Arocutin and Huaniqueo pedregals are the most closely related, both at generic and specific level. This is followed by the pedregal of San Angel in Mexico City and finally the pedregal of Chichinautzin, Morelos. Additionally, traditional uses of some plants are recorded. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la subfamilia de hierbas perennes o anuales Aristidoideae y su única tribu, las Aristideae. Para la subfamilia se indican las características morfológicas y anatómicas, se describe su distribución geográfica y se discurre sobre su presencia en la región de Veracruz, México.

El artículo enfoca en la familia de árboles arbustos o sufrútices, Chrysobalanaceae, la cual se considera parte del orden Malpighiales. Para la familia y sus géneros correspondientes se indican las características morfológicas y anatómicas, se describe su distribución geográfica y se discurre sobre su presencia en la región de Veracruz, México.

We updated the floristic checklist of the Nizanda region, Isthmus of Tehuantepec (southern Mexico), characterized the occurring plant communities based on dominant species, and described the region’s flora according to life form, growth form, growth type, and growth habit spectra. Ten years of botanical exploration, along with surveys in 188 100-m2 samples from different vegetation types, provided the baseline floristic information. Ordination and classification analyses were performed to examine the degree of differentiation between communities. Geographical ranges of all species were used to assess biogeographical relationships of this flora. The inventory includes 920 species (553 genera, 124 families). More than one-third of the families were represented by a single species, whereas the 10 richest families had 43% of the species richness. Dendrograms showing plot classification at three taxonomic levels (species, genus and family) revealed savannah as the most strongly differentiated community amid seven vegetation types. Regarding growth forms, forbs and trees prevailed. Phanerophytes were the most common life form category, whereas herbs and woody plants were the dominant growth types. The largest richness for all taxonomic levels was recorded in the tropical dry forest. The expanded floristic knowledge gained for the Nizanda region provided better criteria to revise the classification scheme of its vegetation. Our preliminary biogeographical analysis illustrates the role of the Isthmus of Tehuantepec as a corridor for thermophilous floras between two oceanic watersheds, and as a natural distributional limit for several Mesoamerican plant species. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la familia de plantas herbáceas acuáticas Hydrocharitaceae y dos de sus géneros,Egeria e Hydromystria. Para las especies Egeria densa y Hydromystria laevigata se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

El artículo enfoca en la familia de plantas herbáceas Anacampserotaceae y sus géneros Anacampseros, Grahamia y Talinopsis. Se menciona que éstos géneros se clasificaban anteriormente en la familia Portulacaceae. Para las especies Anacampseros coahuilensis y Talinopsis frutescens se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y regiones cercanas.

The article provides information on some aspects of the genus Quercus or Mexican oak, including its taxonomy, diversity, distribution, and ecology. It indicates that the genus Quercus is a woody plant found in the Northern Hemisphere and has 500 species worldwide and more than 200 in the Americas. It claims that Mexico has the greatest wealth of species of the genus Quercus because of the prominence of its physical geography.

The article presents the accepted names of oaks in Mexico and neighbouring countries, together with their natural distribution by state. It claims that the distribution data are derived from a report generated from the website http://www.oaknames.org. They include Quercus acherdophylla, Quercus aculcingensi, Quercus acutifolia, and Quercus acutangula.

The article discusses the inventory, use, and distribution of genus Quercus in Tixtla de Guerrero, Mexico. It cites the most important oak species ecologically including Q. magnoliifolia, Q. liebmannii, and Q. acutifolia. It also talks about the economic importance of the oaks of the community of La Estacada. It concludes that the Mexican oak forest is composed of seven species and one variety and the habitats of the species are tropical and deciduous.

El artículo enfoca en la familia de plantas herbáceas perennes Iridaceae y sus 8 géneros (con sus respectivas especias) incluyendo Sisyrinchium, Namastylis y Rigidella. Para cada una de sus especies, se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en la familia de plantas perennes y lepidotas Bromeliaceae y los géneros (con sus respectivas especies) existentes en México, incluyendo los géneros Aechmea, Hechtia y Bromelia. Para cada género y sus especies se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.