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El artículo enfoca en el género de plantas (lianas) Turbina y una de sus especies, Turbina corymbosa. Se indican sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y baja vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas herbáceas o lignescentes Operculina (cercano al género Merremia) y una de sus especies, Operculina pinnatifida. Se indican sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y baja vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el genero de plantas herbáceas rastreras Dichondra y cinco de sus especies incluyendo D. sericea, D. micrantha y D argentea. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas herbáceas Jacquemontia (Choisy) y tres de sus especies, J sphaerostigma, J. nodiflora y J. pentantha. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas herbáceas Evolvulus L. y cuatro de sus especies, E alsinoides, E. prostratus, E. sericeus y E. rotundifolius. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas parásitas herbáceas Cuscuta L. y 15 de sus especies incluyendo C. chapalana, C. obtusiflora y C. campestris. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas herbáceas Cressa L. y una de sus especies, Cressa truxillensis. Se indican sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su escasa presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en la familia de plantas Convolvucaeae II, subgénero Convolvulus L. y cuatro de sus especies, C. rozynskii, C. arvensis, C. crenatifolius y C. equitans. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica general 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 herbáceas Compositae, tribu Helenieae), 12 de sus géneros, incluyendo Flaveria, Bahía y Espejoa y sus 15 especies representadas en México. Para cada género y especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se reporta sobre su presencia en la región de Veracruz, México.

El artículo enfoca en tres especies de plantas herbáceas del género Leersia Sw: L. hexandra, L. ligularis y L. monandra. Para cada una se indica sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad en la zona del Bajío de México y alrededores.

El artículo enfoca en tres especies de plantas herbáceas del género Luziola (Hydrochloa P. Beauv.): L. fluitans, L. gracillima y L. peruviana. Para cada una se indica sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad en la zona del Bajío de México y alrededores.

El artículo enfoca en el género botánico Rumex y cinco de sus especies incluyendo R. pulcher, R. obtusifolius y R. mexicanus. Para cada una de las especies se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas herbáceas Eriogonum y una de sus especies Eriogonum jamesii (var. undulatum). Se indican las características morfológicas y anatómicas de este arbusto, se cita su distribución geográfica general y se describe su escasa presencia y posible vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en la especie de plantas herbáceas Polygonum y seis de sus subespecies incluyendo P. aviculare, P. punctatum y P hydropiperoides. Para cada subespecie se indican las características morfológicas y anatómicas, se cita su uso y distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género botánico Coccoloba y una de sus especies, Coccoloba barbadensis. Se indican las características morfológicas y anatómicas de este árbol, se cita su distribución geográfica general y se describe su escasa presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

El artículo enfoca en el género de plantas Antigonon Endl. y dos de sus especies A. flavescens y A. leptopus. Para cada una se indica sus características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su uso ornamental y baja vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

The article describes the bulb species discovered during the 30-day expedition to Southern Mexico in Winter 2008. A stop at San Louis Potosi showed Tillandsia tortilis growing on pine and oaax trees, and Echeveria agavoides on more hospitable ground. Hechtia matudae and Tillandsia susperinsignis were found on the states of Morelos and Mexico. Meanwhile, on the pine and oak forests, Tillandsia eizzi and Tillandsia ponderosa were discovered.

The potential climatic areas for the distribution of red cedar (Cedrela odorata L.) were obtained in the state of Hidalgo under actual conditions, with meteorological information of 1961-1990 as base line, and under climate change conditions wich were obtained with two models: GFDL-R30 and HadCM3 for two time scenarios (2020 and 2050). The adjustment rates in temperature and rainfall obtained for each model were applied on climatic influence areas delimitated according to Gómez et al. (2006). A soil moisture balance in the state's surface was calculated under current and climate change conditions using the Thornthwaite, modified version III methodology (Monterroso and Gómez, 2003). The present percentage of the state surface with the vegetation types associated with red cedar is of 9,8% and the surface percentage estimated with some degree of suitability for this specie, using the climatic characteristics of the baseline scenario, is of 30,4%. The results of applied GFDL-R30 model shows an increment on the total surface with some degree of suitability with respect of the baseline scenario of 3,1% and 4,4% for the years 2020 and 2050, respectively, with a differential increment within the suitability classes. The surface estimated with some degree of suitability applying the HadCM3 model shows a decrement of 0,9% for the year 2020 and 0,2% for 2050. However, the class of Moderate suitable, change from 10,5% on the baseline scenario to 0% and 1,3% for the years 2020 and 2050, respectively, with almost all the areas in the lowest level of suitability. [ABSTRACT FROM AUTHOR]

El artículo enfoca en la familia de plantas herbáceas anuales Sphenocleaceae y su único género Sphenoclea que incluye las especies S. zeylanica y S. pngatium. Para cada especie se indican las características morfológicas y anatómicas, se cita su distribución geográfica y se reporta sobre su presencia en la región de Veracruz, México.

The genus Polianthes (Agavaceae) is endemic to Mexico and is important at the scientific, economical, and cultural level since prehispanic times. Habitat destruction is one of the main factors affecting populations of Polianthes species, yet little is known about the geographic distribution of this genus, and thus its vulnerability to habitat change. We compared three different approaches to measure the Polianthes species area of distribution to assess the risk of species extinction applying the MER (Method of Evaluation of Risk extinction of wild species for Mexico): area of occupancy, extent of occurrence, and ecological modeling. We also found the richness areas of distribution of this genus. We compared the species distributions with Terrestrial Protected Regions (TPR) and Natural Protected Areas (NPA). Although the three methods used to calculate the species area of distribution agree about the highly restricted nature of Polianthes species. The area of occupancy sub-estimate the species distribution, while the extent of occurrence over-estimate it for species with disjoint distribution. Thus, we recommend the use of ecological modeling to improve the assessment of the current species distribution area to apply the MER. Most Polianthes species are distributed in the Sierra Madre Occidental and Transvolcanic Belt. Three species do not occur in any of the NPA or TPR, one species has suitable habitat in three TPR but has not been recorded there, and one species, P. palustris, is likely extinct. .KWT-Keywords: [ABSTRACT FROM AUTHOR]

The nomenclatural statuses of Tillandsia parryi Baker and T. sueae Ehlers are clarified, and 72 suesilliae is described as new. Data relative to the distribution, ecology and phenology of the studied taxa are provided. [ABSTRACT FROM AUTHOR]

As currently defined, the 24 species of Schoenocaulon occur in three disjunct areas: north central Florida (one species, S. dubium), southern Peru (portion of the range of S. officinale), and the region from southeastern New Mexico-Texas south to Venezuela; the 20 species endemic to Mexico are geographically restricted. Species delimitations, often based on tepal morphology, have been problematic. Our analyses of ITS sequence data for all 27 species and infraspecific taxa support recognition of two new species and recircumscription and placement of elements of the polyphyletic S. ghieshreghtii and S. mortonii complexes. For taxa with adequate sampling, our data also indicate 11-12 cladospecies and 3-6 metaspecies according to the apomorphic species concept. The resolved phylogeny, correlated with geography and morphology, allows insight into biogeographical diversification and the evolution of some unusual morphological characters within the genus, such as nectary differentiation and tepal margin type. [ABSTRACT FROM AUTHOR]

Aim The purpose of the study was to assess the degree of floristic differentiation between tropical dry forest (TDF) and savanna occurring in a single landscape. This comparison provides information on the responses of vegetation to the prevailing environmental conditions, while it also allows us to make inferences about large-scale events and processes, both biogeographical and evolutionary. Our approach included three levels of analysis: (1) taxonomic, (2) morphological and (3) vegetational. Location The seasonal dry tropical landscape in the Nizanda region, Oaxaca State, southern Mexico. The landscape comprises a complex vegetation mosaic in which tropical dry forest and savannas are the most conspicuous components. Methods Comparisons between TDF and savanna were based on inventories for these communities produced after 8 years of botanical survey. At the taxonomic level, the relative representation of taxa of different hierarchical levels in each community was examined. Morphological analyses required the classification of species on each of three criteria: (1) growth form, (2) life form and (3) growth habit. Vegetation level analysis was based on the frequencies of taxa in one hundred 100-m2 composition plots with which matrices of binary data were constructed for species, genera and families. These were subjected to classification analysis with Ward's method and using Euclidean distances as the dissimilarity algorithm. Results The combined flora for both communities comprised 600 species, 375 genera and 94 families; between them they shared 31, 40 and 34 taxa, respectively. The corresponding Sørensen similarity values were 10%, 21% and 72%, respectively. Ranking genera and families according to their species richness displayed large differences between savanna and TDF. Large differences between these communities were observed for Acanthaceae, Cactaceae, Euphorbiaceae and Mimosaceae, whereas Fabaceae and Asteraceae had similar high ranks according to the species richness in the two systems. The growth form spectrum diverged between the two communities, with TDF having more trees, shrubs and climbers. Savanna was characterised by forbs and graminoid herbs. Growth habit spectra revealed a clear dominance of herbaceous and suffruticose plants in savanna, and of woody elements and epiphytes in TDF. Regarding Raunkiaer's life forms, savanna had relatively more hemicryptophytes, and TDF more phanerophytes. Classification analyses showed that savanna and TDF forest samples kept their identities, regardless of taxonomic level (species, genera and families) at which the analyses were performed. Main conclusions The TDF and savanna of Nizanda represent two floristic systems with a large degree of differentiation at all taxonomic levels and patterns of morphological attributes. This suggest that the two floristic sets have evolved independently for extended periods of time, despite their close proximity. One important implication of this floristic differentiation is the large joint contribution made by these communities to the regional flora. [ABSTRACT FROM AUTHOR]

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Thecal morphology was studied, with an emphasis on sulcal plates, in 17 mainly tropical-boreal and tropical Protoperidinium species from the southeastern Mexican Pacific Ocean: P. brochii, P. claudicans, P. conicum, P. crassipes, P. depressum, P. divergens, P. elegans, P. excentricum, P. grande, P. latispinum, P. minutum, P. obtusum, P. oviforme, P. pentagonum, P. punctulatum, P. venustum and P. vulgare. These data were compared with those in published literature on the morphology of sulcal plates. Records of the species in the study region were compiled, and maps of global distribution for 11 are presented. The range of intraspecific variability in the morphology of sulcal plates still remains largely unknown, and accumulated relevant data need to be evaluated properly. [ABSTRACT FROM AUTHOR]

The presence of vines has been described as a distinctive feature of tropical forests. However, vine species diversity exhibits trends across environmental gradients that are not well documented. Here we use a latitudinal and a rainfall gradient along the Pacific slope of México to explore the influence of environmental factors on vine species diversity. A total of 630 vines species were detected on the Pacific slope of México. Tropical deciduous forest (TDF) floras were composed of greater percentages of vines (5–16%) than desert floras (1–3%). Four families (Convolvulaceae, Fabaceae, Cucurbitaceae and Asclepiadaceae) composed 40–60% of the vines of the region. Changes in vine composition were gradual along the Pacific slope. The percentage of vines in floras declines with latitude. Annual rainfall and the minimum temperature of January were significantly associated with the latitudinal decline in the percentage of vines. A total of 43 species, mostly herbaceous vines, were detected along a rainfall gradient in northwestern México. Along the rainfall gradient, the number of vine species increased from 3 to 28 as summer rainfall, plant cover and canopy stature increased. Vine species richness and diversity increased from the desert to the TDF, especially along streams. Leaf area (LA) ranged from 0.6 to 284 cm2 and specific leaf area (SLA) from 80 to 904 cm2/g among the most common vine species. Community averages of LA and SLA decreased toward drier sites. These results are discussed within the context of our current knowledge about the role of the environment in limiting the distribution of vines. [ABSTRACT FROM AUTHOR]

We report, for the first time, the presence of Nierembergia angustifolia in the state of Jalisco, Mexico. The distinctive characteristics of this species and an update of its known geographical distribution are discussed. [ABSTRACT FROM AUTHOR]

The Poaceae family includes approximately 700 genera and 10 000 species, and Mexico is considered one of its most important centers of diversity and endemism. A total of 256 taxa (including 16 subspecific taxonomic units), belonging to 65 genera, are endemic to Mexico. Some of them are close relatives of important crops, while others are used in different ways all over the country. The aim of this paper is to discuss the distribution patterns at state level of the Mexican endemic species of Poaceae. Using cluster strategies, the states are classified according to their floristic similarities. Later, hotspots of endemism are identified, in order to discuss their role in conservation strategies. To evaluate the importance of each state in the conservation of the Mexican endemic Poaceae, two iterative complementarity methods were also used. Our results show that the largest concentration of endemic taxa occurs in a few states, such as Jalisco, Mexico, Michoacán, Durango, Oaxaca, Veracruz, San Luis Potosi, Chiapas, Chihuahua, Puebla, and Coahuila. The results also show that there are some patterns in the relationship to its endemism that seem to reflect important diversification trends in the family. Accordingly, 31% of the grass genera of Mexico have at least one endemic species, and 16.7% of the genera have only one endemic species. In contrast, six genera contribute 47.2% of the total number of grass endemics in Mexico. The Chloridoideae contributes 42.9% of the total grass endemic species of Mexico, whereas the Panicoideae includes 24.6%, and the Pooideae 19.8%. Thus, these three subfamilies contribute about 87% of the species endemism. On the basis of the habitat and distribution patterns of these subfamilies, two main areas of endemicity can be identified. The first area is located in warm habitats, whereas the second is related to temperate and high regions. The cluster analyses indicate the occurrence of four state groups whose phytogeographical explanation is discussed on the basis of a floristic regionalization of Mexico. The results also indicate the need to establish a relatively high number of sites and states for the conservation of 256 endemic taxa. The elevated number of sites required to conserve the Mexican endemic Poaceae is mainly due to the fact that many taxa have a restricted distribution pattern. On the basis of the patterns obtained, a few proposals are presented for undertaking the establishment of conservation priorities of these taxa. [ABSTRACT FROM AUTHOR]

The circumscription and distribution of Tillandsia dasyliriifolia are here clarified, as well as the differences with other species in what we refer to as the Tillandsia utriculata (L.) L. complex in Mexico. Aspects of reproductive biology, including pollinators of natural populations of Tillandsia dasyliriifolia in northern Yucatan State, indicate that the populations of the species in the study site are not presently in danger due to the large reproductive capacity of the species through sexual reproduction and vegetative growth. [ABSTRACT FROM AUTHOR]

The genus Ceratozamia contains more than 20 species distributed in eastern and southern Mexico, with extensions into Central America. Morphology, anatomy, and molecular (ITS) data allow resolution of some aspects of species relationships, provide correlations with ecology, and suggest phytogeographic hypotheses. Some species complexes, such as those centered around C. norstogii and C. miqueliana, are restricted to southernwest Mexico, in what are regarded as Pleistocene floristic refugia. The low level of divergence of ITS sequences among taxa to the north of the Trans-Mexican Neovolcanic mountain range suggests a pattern of recent, and perhaps rapid, speciation. [ABSTRACT FROM AUTHOR]

The eelgrass Zostera marina L. is distributed along the Baja California Peninsula (Mexico) where it is exposed to a wide range of irradiances and temperatures that could promote changes in its biochemical composition. Consequently, the objective of this study was to characterize the variations in the levels of chlorophyll, carbohydrates, proteins, fiber, ash and calories in the shoots of Z. marina from the north (San Quintín) and south (Ojo de Liebre and San Ignacio lagoons) of the peninsula. Temperature in the southern lagoons was 5-6°C higher than in the northern lagoon; likewise, in situ irradiance was two-fold greater in the south than in the north. As a result of the lower irradiance levels, the concentration of chlorophyll in the shoots of Z. marina was twice as high (1.7 mg gWW-1) in the northern lagoon than in the southern ones (0.8 mg gWW-1). Similar to chlorophyll levels, the concentration of soluble carbohydrates in the shoots was greater in the northern lagoon than in the southern ones, suggesting that the high levels of chlorophyll are enough to compensate for the low irradiance levels and to maintain a positive carbon balance at San Quintín. On the other hand, the levels of proteins in the shoots from the north of the peninsula were slightly lower than those from the southern populations. In general, these results suggest that the different environmental conditions to which Z. marina is exposed along the peninsula impact its biochemical composition. [ABSTRACT FROM AUTHOR]

A phytosociological study of 59 relevés was carried out at Laguna Quila, National Park Lagunas de Zempoala, México, using the Zürich-Montpellier approach. Eleven communities were identified and described. A distinction was made between a submerged and a helophytic hydroseral vegetation. A pronounced humidity gradient was identified in a north-south direction, and also a continuous desiccation was observed. A vegetation map scale 1:1900 is included. 21 families of vascular plants including 41 species and 33 genera have been identified. Families best represented include Cyperaceae with seven species and Ranunculaceae with four species. Phytogeographical analysis on the generic level revealed that the temperate component reached 65%, the cosmopolitan 30% and the tropical 5%. The species of Laguna Quila have a wide distribution in Mexican hydroseries and elsewhere in temperate America. Aquatic and semi-aquatic communities are vanishing rapidly in Mexico, and it is important to understand the dynamics for adequate management of this natural resource. In order to protect this lake it is recommended to control the water extraction of the laguna, to exclude cattle and other activities who can affect indirectly Laguna Quila. [ABSTRACT FROM AUTHOR]

Two species of Valeriana of apparently very restricted distribution are described as new. V. emmanuelii, collected in two localities of the southern extreme of the municipality of Morelia, Michoacán, is related to V. retrorsa Fern. and to V. densiflora Benth. V. zamoranensis belongs to the series Ceratophyllae and is only known from the highest part of Cerro Zamorano; it seems to be related to V. zapotecana Barrie and to V. otomiana Barrie. [ABSTRACT FROM AUTHOR]

Presents a study that identified an assemblage of leaves and leaflets under five species of the genus family of Anacardiaceae collected from the Oligocene Los Ahuehuetes locality of Puebla, Mexico. Description of the species; Biogeographic relationships; Synecological relationships.

Population size distributions were examined for 12 species of trees co-occurring at Chamela Biological Station in Jalisco, Mexico. Species had been selected as congeneric pairs and trios similar in gross morphology and ecology in order better to identify correlates of relative abundance. Rarer species were found unanimously to have more irregular distributions of individuals among size classes than more common species when distributions were compared to a smooth, descending curve constructed from population mean stem diameters (an exponential distribution). Examination among species of patterns of deviation from these corresponding smooth distributions indicates that the most reasonably inferred cause for the observed pattern is consistent differences in degree of fluctuation in recruitment into adult size classes. These results thereby suggest a demographic difference between locally rarer and more common species that may be generally associated with observed differences in relative abundance and indicate a focus for management of rarity in forest trees. [ABSTRACT FROM AUTHOR]

We report, for the first time, the presence of five species of Solanum for the Bajío and neighboring regions flora. Solanum brachistotrichum, S. hintonii, S. jamesii y S. morelliforme are grouped in Solanum section Petota while S. triquetum is part of Solanum section Dulcamara. We highlight the distinctive characteristics of each species and update their known geographical distribution. Finally, we present a drawing of S. triquetrum. [ABSTRACT FROM AUTHOR]

The vegetation and the vascular plants of an ecotonal zone between the floristic provinces of the Desert Plateau (Chihuahuan Desert) and Gulf Coastal Plain in northeastern México were studied. The study zone has a surface of 2,526.25 km² and it is located in the northern part of the state of Nuevo León. On the basis of physiognomy, ecological characteristics and dominant species, seven types of vegetation were recognized. With the aid of 50 sampling plots, aerial photographs and floristic composition, the units of vegetation were delimited and mapped. 405 species (varieties and subspecies included) were identified. The study zone showed geographical affinity with the vegetation of the Chihuahuan Desert in the Desert Plateau of México (Hilaria mutica grassland, low thornless scrub of Flourensia cernua and medium size mixed scrub of Acacia-Prosopis-Flourensia-Larrea) and with the Gulf Coastal Plain (medium size mixed scrub of Leucophyllum frutescens and Acacia rigidula and high mixed scrub of Helietta parvifolia). The medium size and high thorny scrubs of Prosopis-Acacia showed no clear relationships with any of the floristic provinces. The coexistence of shrubby vegetation characteristic of the lowlands in the Gulf Coastal Plain and the vegetation usually present in the Chihuahuan Desert, can be explained in view of the increment of aridity and gentle raising of the continental surface in east-west direction, and of the absence of notable topographic accidents in the northeastern region of México. [ABSTRACT FROM AUTHOR]

Aim The floristic affinities between Cuba and the Yucatán Peninsula are of great interest for plant geography and preservation of biodiversity in the Caribbean region. Although many authors have stressed the relationship between these regions, the conclusions are based mostly on general descriptive studies. Here we present a quantitative analysis in order to determine their floristic affinities. Location We compared the Mexican portion of the Yucatán Peninsula (states of Campeche, Yucatán and Quintana Roo) and several karst areas of the Cuban Archipelago; which were selected because of the great physiographic, climatic and vegetational similarities. Methods Data obtained from specialized references were used to create a taxonomic data base, this was complemented with a data base (D-BASE) that included data from herbarium specimens. Geographical information was obtained and adapted for use in a numerical taxonomy and multivariate system program (NTSYS). Using the latter, we performed a floristic affinity analysis using a monothetic method based on the comparison of the presence and absence of species. Floristic similarity was obtained using the Jaccard index of similarity and a dendrogram was created. Results Of a total of 1936 species, 880 were common to both Yucatán and Cuba; most being herbaceous species, followed by trees and bushes. The flora of Mexican island of Cozumel exhibited the lowest coefficient of similarity (11%) when compared with the rest of the sites considered. The second level in the dendrogram shows the branching of two large groups: the three states of the Yucatán Peninsula and the coastal areas of Cuba, and the Cuban interior. Highest similarity (73%) within the Cuban areas considered was obtained between the Isla de la Juventud and the Guanahacabibes peninsula; both areas also showed the highest floristic similarity with the Yucatán Peninsula (67%). The Cuban keys and the coastal plain of Tunas form a second group of Cuban localities that exhibited a relatively high floristic affinity with the Yucatán Peninsula. The areas of Maisí, Morrillo and Chico, in east Cuba, form a group with considerably high similarity (50%), and are physically the closest to Yucatán after the Coco–Romano–Caguanes group. The Cuban areas below 600 m in elevation were the least similar to the Yucatán Peninsula. Main conclusions Despite earlier suggestions, there are various areas of Cuba that have close floristic affinity with the Yucatán Peninsula, sometimes based on the presence of specific taxa, and other times based on large groups of taxa common to both study areas with different and broader types of distribution. The number of species (880) common to both the Yucatán Peninsula and the different karst areas of the Cuban Archipielago surpasses all expectations, as the native flora of the Yucatán Peninsula is estimated to have at least 1777 species, and if we exclude exotic, introduced and cultivated species, the general floristic similarity between Cuba and the Peninsula of Yucatán should be about 50%. [ABSTRACT FROM AUTHOR]

Laurencia venusta Yamada, originally described from the western Pacific Ocean, is recorded for the first time from the Atlantic Ocean. It occurs in Quintana Roo State, Mexico, which is located on the eastern portion of Yucatan Peninsula, Caribbean Sea. The present species belongs to the subgenus Laurencia by nature of possessing four pericentral cells per vegetative axial segment, secondary pit-connections between superficial cortical cells, and parallel-type arrangement of the tetrasporangia. The principal characteristics for species identification are: pale green color, soft and flaccid thalli, verticillate branching, and the presence of lenticular thickenings in the walls of medullary cells. [ABSTRACT FROM AUTHOR]

A track analysis based on the distributional patterns of 967 species of vascular plant taxa (gymnosperms, angiosperms and pteridophytes) was performed to assess conservation priorities for cloud forests in the state of Hidalgo, Mexico, ranged in the municipalities of Chapulhuac´m, Eloxochitl´m, Molocotl´m, Pisaflores, Tenango de Doria, Tlahuelompa and Tlanchinol, as well as five floristically equivalent areas in the states of Veracruz (Teocelo and Helechales), Tamaulipas (Gómez Farías), Morelos-México (Ocuilan) and Oaxaca (Huautla de Jiménez). In order to detect generalized tracks we employed a new parsimony method, where clades (considered equivalent to generalized tracks) are defined forbidding homoplasy and acting like a compatibility algorithm. Several generalized tracks were found connecting these areas. Cloud forests of Chapulhuacán were connected according to three different generalized tracks and thus have a higher value, qualifying as a priority area for the conservation of cloud forests in the state of Hidalgo. [ABSTRACT FROM AUTHOR]

A check list of vascular plants consisting of 89 families, 208 genera and 288 species is presented. The study area, called Sierra de Nanchititla, is located in the southwestern region of the State of Mexico, near the borders with Guerrero and Michoacán. The families Asteraceae, Pteridaceae, Burseraceae, Fabaceae, Mimosaceae and Rubiaceae are best represented. Geographical distribution of families and genera is analyzed. The elements of tropical affinity are dominant. Complementary data on phenology of some life forms are provided as well as information about the state of conservation of original vegetation. [ABSTRACT FROM AUTHOR]

Quercus gambelii Nutt. is a widespread white oak (Quercus, subgenus and section Quercus, subsection Gambelieae) in the southern Rocky Mountain region of the United States, extending to west-central Chihuahua in the Sierra Madre Occidental of Mexico. Quercus arizonica Sarg., rather distantly related (subsection Glaucoideae), has a more southern distribution in the United States, and extends through the Sierra Madre into Durango. In the southwestern United States hybrids between Q. gambelii and several white oaks, including Q. arizonica, are very common, often forming a major portion of the lower elevation oak vegetation, particularly in New Mexico. These hybrids are known in general as Q. x undulata Torr., pro sp. A plant very similar to Q. x undulata, Q. lesueuri C. H. Muller, was collected by Harde LeSueur at "El Salto de Babicora", in west-central Chihuahua, in 1937. It has not been collected since. An oak similar to Q. lesueuri was collected by the author in the nearby Sierra Catarina where it is sympatric with Q. gambelii and Q. arizonica. El Salto de Babicora was determined to be located north of the town of Madera. In this canyon Q. gambelii and Q. arizonica are common. Quercus lesueuri and the newly collected hybrid from the Sierra Catarina are shown to be strongly similar to Q. x undulata and intermediate between Q. arizonica and Q. gambelii through the use of the same six leaf characters (leaf width, relative depth of indentations of leaf margin, conspicuousness of intercostal reticulum, number of major secondary veins, number of rays per stellate hair, curliness of hairs) that Tucker used to assess intermediacy of certain collections to the putative parents Q. gambelii and Q. arizonica. In this paper Q. lesueuri is demonstrated to be part of this hybrid complex. Taxonomically it should be recognized as Q. x lesueuri C. H. Muller, pro sp., and to be considered as a synonym of Q. x undulata, sensu lato. [ABSTRACT FROM AUTHOR]

Commelina nivea López-Ferrari, Espejo et Ceja, and Commelina rzedowskii López-Ferrari, Espejo et Ceja, two white flowered species are described and illustrated in this paper. The former is known only from Las Adjuntas, municipio of Pueblo Nuevo in the state of Durango and the other was collected in the neighborhood of Tenería, municipio of Tejupilco in the state of México. [ABSTRACT FROM AUTHOR]

The present status of the floristic-ecological knowledge of wild Mexican Iridaceae is defined. 16 genera and 98 species of Iridaceae, all of them belonging in the 4 tribes of the subfamily Iridoideae are registered from the country. The tribe Tigridieae has its principal center of radiation in Mexico, where 11 of 18 genera and 52 of approximately 130 species grow; of those, 3 genera (30 %) and 38 species (71.7 %) are endemic. One naturalized species is also known. The best represented genera of Iridaceae in Mexico are Sisyrinchium (40 spp.) and Tigridia (29 spp.). Endemism in the family at species level reaches 54.6 %. Data and comments on habitat, distribution and phytogeography of Mexican Iridaceae are included. [ABSTRACT FROM AUTHOR]

A successional role for each phytogeographical group of seral stands of the pine-oak forests in the Highlands of Chiapas (southern Mexico) could be established after their structural analysis. Most of the Holarctic elements regenerate in early successional conditions, while the regeneration of many Andean and East Asian elements is restricted to the more advanced stands. Forest structure and floristic composition appears as the result of a mixture of species belonging to genera of diverse origin. Their local coexistence seems to depend on their tolerance to those environmental conditions resulting from forest development through succession. We ascribe a central role to the canopy species belonging to Holarctic genera which determine the understory microhabitat for most of the remaining woody species, notably for those of Andean affinity. [ABSTRACT FROM AUTHOR]

This paper presents a complete list of hermatypic coral species, analyzes the biodiversity levels and describes the biogeographic patterns of the group in the Mexican Pacific. The coral fauna of the MexicanPacific consists of 23 species, which makes this region one of the highest in terms of specific richness within the tropical eastern Pacific. In general, the species are grouped in faunistic units that correspond to the traditional zoogeographic provinces recognized in the region. There is no evidence of effective biogeographic barriers throughout the Mexican Pacific region. Local extinction events, likely caused by the narrow distribution of some species, and perhaps due to the type and frequency of transpacific colonizations, modify the normalprocesses of community succession, causing the Mexican Pacific to bea highly dynamic zone in terms of its coral fauna. [ABSTRACT FROM AUTHOR]

The article presents a study on the mangrove ecology and the deltaic geomorphology specifically in some areas off Tabasco in Mexico. It highlights the significance of physiographic-ecological relationship in alluvial coasts. Coastal plant distribution and geomorphic processes were recorded along with the extent of vegetation communities and landform units. Mangroves along the Grijalva-Usumacinta Delta in Tabasco and Campeche in Mexico were the subject of this investigation. Information were observed on distribution, relation to landforms, and the dynamic ecology in response to changes in geomorphology.

El artículo enfoca en la familia de plantas herbáceas Crassulaceae y nueve de sus géneros incluyendo Tillaea, Bryophyllum y Sedum. Para cada género se indican las características morfológicas y anatómicas, se cita su distribución geográfica general y se describe su presencia y vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

Walker's Manihot, Manihot walkerae, is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion of extreme southern Texas and northeastern Mexico. M. walkerae populations are highly fragmented and are found on both protected public lands and private property. Habitat loss and competition by invasive species are the most detrimental threats for M. walkerae; however, the effect of climate change on M. walkerae's geographic distribution remains unexplored and could result in further range restrictions. Our objectives are to evaluate the potential effects of climate change on the distribution of M. walkerae and assess the usefulness of natural protected areas in future conservation. We predict current and future geographic distribution for M. walkerae (years 2050 and 2070) using three different general circulation models (CM3, CMIP5, and HADGEM) and two climate change scenarios (RCP 4.5 and 8.5). A total of nineteen spatially rarefied occurrences for M. walkerae and ten non-highly correlated bioclimatic variables were inputted to the maximum entropy algorithm (MaxEnt) to produce twenty replicates per scenario. The area under the curve (AUC) value for the consensus model was higher than 0.90 and the partial ROC value was higher than 1.80, indicating a high predictive ability. The potential reduction in geographic distribution for M. walkerae by the effect of climate change was variable throughout the models, but collectively they predict a restriction in distribution. The most severe reductions were 9% for the year 2050 with the CM3 model at an 8.5 RCP, and 14% for the year 2070 with the CMIP5 model at the 4.5 RCP. The future geographic distribution of M. walkerae was overlapped with protected lands in the U.S. and Mexico in order to identify areas that could be suitable for future conservation efforts. In the U.S. there are several protected areas that are potentially suitable for M. walkerae, whereas in Mexico no protected areas exist within M. walkerae suitable habitat. [ABSTRACT FROM AUTHOR]