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Jatropha chazaroi is described and illustrated as a new species from the state of Veracruz, Mexico. It is morphologically similar to J. podagrica but is distinguished by being a tree or shrub devoid of a caudex (vs. shrub with caudex) and lacking persistent and spinescent stipules (vs. having persistent and spinescent stipules). Its flowers possess connate staminate and pistillate calyces and corollas (vs. not connate). Jatropha chazaroi is only known from the municipality of Apazapan, Veracruz, and thrives in shady sites throughout intermittent waterways.

Hymenocallis ximixtlanensis is described and illustrated as a new species for science. This taxonomic entity has similarity with H. graminifolia. However, it is distinguished from the latter by presenting wider leaves (1.9–2.2(–2.8) vs. 0.5–0.7 cm), much longer floral tubes (12–14.2 vs. ca. 4 cm), longer anthers (ca. 2 vs. 1.4 cm), and ovaries with four ovules in each locule (4 vs. 2).

Opuntia tehuacana and Opuntia olmeca are morphological similarity and have been considered during the time as the same species. However, neither a detailed morphological study nor a phylogenetic assessment has been made to confirm this statement. In fact, although several phylogenetic studies of the genus Opuntia have been carried out, both species have not been sampled to know their phylogenetic relationships. The present study is based on a morphological comparison of the two taxa, based on both live and herborized individuals. A total of eighteen sequences were generated, six ITS, six matK, and six trnL-F. and a phylogenetic analysis was performed based on Bayesian inference. The results obatined provides evidences that support O. olmeca and O. tehuacana as the same species.

Cycads are a group of plants in the order Cycadales, comprising ten genera, and with a worldwide distribution. Very few taxonomic revisions are available for the genera in this order, and the present one is intended to provide a revision of the current knowledge in the genus Dioon. The revision was based on bibliographic research and analysis of herbarium specimens, including live specimens found in different botanical gardens and greenhouses. Sixteen species are recognized for the genus. This study includes morphological descriptions, maps with species distribution, line drawings of diagnostic characters, and a key to the species. Detailed taxonomic notes for each species, as well as information on their distribution and habitat is provided, including the uses and common names when available. Fifteen of the total species are distributed in Mexico and one species is found in the border of Honduras and Nicaragua. Therefore, the genus is endemic to Megamexico II.

A detailed morphological and molecular study on Opuntia matudae and O. hyptiacantha is presented. These two species have been long considered to belong to the same taxon, although no investigations were carried out in depth. Moreover, no published phylogenetic study of the genus Opuntia include both species. Our data support the recognition of O. matudae and O. hyptiacantha as different and unrelated species.

Background: The family Fagaceae is one of the most important in temperate regions of the Northern hemisphere. Fagus and Quercus are distributed in Mexico, the former in Northeastern Mexico, while the latter reaches a high diversity in the Sierra Madre Oriental, Mexico. In Hidalgo state, located mainly in the Sierra Madre Oriental, knowledge of the Fagaceae diversity is still uncertain. Questions and/or hypothesis: We carried out a taxonomic revision of the genus and species of Fagaceae in Hidalgo state. We determined how many and which species are distributed in Hidalgo. We also present a morphological description and ecological characters of each one. Studied species: The species of the family Fagaceae Study site: Hidalgo state, Mexico. Method: We collected herbarium specimens, made field observations and reviewed herbarium data of Fagaceae specimens at FCME, INEGI, MEXU, ENCB, SLPM, HUMO, XAL and partly BH herbaria. In addition, we checked taxonomic literature and protologues of each species. Results: We found one species of Fagus and 43 of Quercus , 22 of which belong to the section Quercus (white oaks) and 21 to section Lobatae (red oaks). Morphological descriptions, altitudinal and geographical distribution, vegetation types of each species and a dichotomous key for species identification are presented. Illustrations and photographs of the species are also included. Conclusions: A high diversity of Fagaceae species is present in Hidalgo state. In Mexico, Hidalgo ranks in fifth place for oak species diversity, just behind Oaxaca (50 species), Puebla (50), San Luis Potosí (45), and Jalisco (45).

Jatropha spp. from Mexico includes high species richness and endemism; five species inhabit in the Tehuacan-Cuicatlan Biosphere Reserve (TCBR), and they are important resources as food, medicine and biofuel. The assessment of morphological and agronomic characteristics is essential to identify, use and maintain plant genetic resources. Given the lack of information on the morphological variability of Jatropha species in relation to environment, the objective was to analyze the influence of physiographic, climatic, and anthropogenic factors in the morphological variability of the species: Jatropha neopauciflora and J. rzedowskii, both not-endangered; J. oaxacana, special protection; J. ciliata and J. rufescens, both endangered in the Reserve. Twelve quantitative morphological variables were measured in 24 populations of these species; 14 environmental variables were registered, and the disturbance index in the sites was estimated. The information was analyzed with Principal Components Analysis (PCA), Cluster Analysis and Canonical Correspondence Analysis (CCA). PCA detected interspecific variation: J. ciliata and J. rufescens have longer and broader leaves and longer flowers, while the other three species have smaller leaves and flowers. J. oaxacana population has intermediate size of leaves, fruits and seeds, compared with those of J. neopauciflora and J. rzedowskii. CCA detected intra-specific variation among the populations of J. neopauciflora and J. rzedowskii, which were separated in two groups due to fruit and seed size. Axis 1 of CCA correlated positively with altitude and annual temperature range, and negatively with mean annual temperature; at the intra-specific level, both species are adapted to variations of temperature and altitude.

This study has two main objectives: a) to provide, for the first time, a detailed description of the macro- and micromorphology of Opuntia joconostle based on collected specimens; and b) to generate a first phylogenetic analysis, which will help to resolve the taxonomic and nomenclatural status of this species.

Desmopsis guerrerensis, a new species endemic to Guerrero, Mexico is described and illustrated. The new species is related to Desmopsis verrucipes, endemic to Costa Rica, but it differs in several morphological characters and geographical distribution. A key to the species of Desmopsis of Mexico and Central America that have persistent sepals in fruit is presented.

Ipomoea discoidea is described and illustrated as a new species from the states of Guerrero and Jalisco, Mexico. The new species shares close affinities with I. macdonaldii and I. lottiae, and is a creeper with widened, disk-shaped receptacle, fleshy calyx, hypocrateriform white corolla, exserted stamens and style, and seeds with long trichomes on the margins. Ipomoea discoidea grows in deciduous and subdeciduous forest.

Se describe e ilustra a Picramnia thomasii, como una especie nueva del estado de Guerrero, Mexico. La especie nueva se relaciona con P. guerrerensis, pero difiere por tener foliolos con indumento en enves, inflorescencia estaminada de mayores dimensiones y con mas glomerulos, petalos de forma y color diferente, estambres con mayor longitud, frutos indumentados, semillas mas pequenas y distribucion conocida hasta el momento en selva baja subcaducifolia de Acahuizotla.

Background Genomic DNA extracted from species of Cactaceae is often contaminated with significant amounts of mucilage and pectin. Pectin is one of the main components of cellular walls, whereas mucilage is a complex polysaccharide with a ramified structure. Thus, pectin- and mucilage-free extraction of DNA is a key step for further downstream PCR-based analyses. Results We tested our DNA extraction method on cladode tissue (juvenile, adult, and herbaria exemplars) of 17 species of Opuntia Mill., which are characterized by a large quantity of pectin and mucilage. Conclusion We developed a method for the extraction of gDNA free of inhibitory compounds common in species of Opuntia Mill., such as pectin and mucilage. Compared to previously extraction protocols, our method produced higher yields of high-quality genomic DNA.

Natural hybridization between an insular endemic species and a widely distributed congener may endanger the endemic through genetic assimilation or outbreeding depression. Furthermore, hybrids can exhibit complex morphological variation, causing taxonomic problems in the identification of the involved taxa. In this work, we used a combination of leaf morphological and molecular markers (RAPD) to establish the differentiation between Psidium sp. aff. sartorianum and the insular endemic P. socorrense. It was also determined if hybridization between these taxa occurs in the southern slope of Isla Socorro, Mexico. Plant collection was carried along an altitudinal gradient (100–800 m). We collected eight populations separated 100 m a.s.l. apart from each other; 25 individuals were collected per population. Psidium socorrense and P. sp. aff. sartorianum differed significantly in all but two morphological characters measured. Also, a high number of diagnostic RAPD markers were found for each taxon. These results suggest that two Psidium species occur at Isla Socorro. Furthermore, both morphological and RAPD markers revealed a hybrid zone located in the southern slope of Isla Socorro (400–700 m a.s.l.) with an asymmetrical pattern of gene flow towards P. socorrense. We suggest that the disturbance caused by the sheep population in the mixed stand favors the establishment of hybrids. We further discuss whether hybridization represents a threat to the insular endemic P. socorrense.

Megastigma balsense, from the Rio Balsas basin, in Guerrero, Mexico, is described as new and illustrated. It is related to M. galeottii.

Natural hybridization frequently promotes gene introgression among closely related species in sympatric populations, producing complex patterns of morphological variation. Therefore, a detailed understanding of the dynamics of interspecific gene flow and its morphological patterns is of widespread interest. We tested if introgressive hybridization promotes an increase in transgressive characters in comparison with the parental species. A sunflower species complex occurring in Mexico formed by two native invasive species, Tithonia tubaeformis and Tithonia rotundifolia, was analyzed using 46 morphological characters (leaf, flower and fruit) in five hybrid zones (N = 150 individuals) and two pure sites for each parental species (N = 80 individuals). In general, T. tubaeformis differed significantly from T.rotundifolia in all the examined characters, except six foliar and one inflorescence character. Morphological characters support the hypothesis of hybridization in this complex, even though both species remain morphological distinct in mixed stands. Individual hybrids appear to be a mosaic of parent-like (24.8 % of traits), intermediate (26.1 %) and transgressive (37.8 %) phenotypes (the remaining 11.3 % of the traits did not differ significantly from both parental species). Our results suggest that individuals from the same parental species were more similar among themselves than to putative hybrids, indicating occasional hybridization with segregation in hybrid types or backcrossing to parents. Evidence indicates a unidirectional pattern of gene flow toward T. rotundifolia.

A new species from the Balsas river basin in Guerrero state, Mexico, is described and illustrated: Lepidagathis danielii (Acanthaceae). This new species is distinguished from all the known species of the genus because it has leaves and bracts with an apical spine, inflorescences with decussate flowers, a calyx with connate lobes of equal length, a red corolla that is 3 cm long and conspicuously bilabiate with a constriction near the base where the stamens are also inserted. In addition, the style is covered with scattered trichomes and the pollen is tricolporate without pseudocolpi.

Se describe e ilustra Holographis lizethae (Acanthaceae), una especie nueva de Guerrero, Mexico. Esta especie guarda similitud con Holographis pallida, sin embargo difiere de ella por presentar margen de la hoja revoluto, bracteas deltadas, cimbiformes, la corola mas grande y con posicion vertical en antesis, los estambres y estilo mas largos, asi como distribucion y periodo de floracion diferentes.

Resumen. Se describe el genero Balsas J. Jimenez Ram. & K. Vega con una especie nueva, B. guerrerensis Cruz Duran & K. Vega (Paullinieae, Sapindaceae), de la Depresion del Rio Balsas en el estado de Guerrero, Mexico. Balsas se distingue de Paullinia L., por presentar capsulas septifragas carnosas con alas proximales, dehiscencia que inicia proximalmente, semillas sin arilo y polen hemitrisincolporado.

Jatropha mirandana J. Jimenez Ram. & K. Vega (Euphorbiaceae), a new and endemic species from the Balsas River Depression, is described and illustrated. This species is similar to J. ciliata Sesse ex Cerv., but differs from it by having the petiole, leaf blade, peduncle, and staminate cyme of smaller size; there are also differences in the type of bark, the shape of the leaf blade, and in the color and shape of the pistillate corolla.

Megastigma chiangii is described and illustrated. It is distinguished from related species by its pentamerous flowers, inflorescences with more than 40 flowers, and distribution restricted to cloud forest vegetation in the Sierra Madre del Sur in the state of Guerrero, Mexico. A key to the species of Megastigma is included.

Prockia jaliscana is described and illustrated as a new species from the state of Jalisco, Mexico. This species is similar to P. oaxacana; however, it differs from the latter because it is dioecious, presents linear or lanceolate to foliaceous stipules, has male and female flowers different from those of P. oxacana, apetalous staminate flowers and presents an ovary with ovules in both basal and parietal placentae.

A new species of Ipomoea, I. kahloiae, is described and illustrated. It is endemic to tropical semideciduous forests in the Acahuizotla area of the Sierra Madre del Sur in Guerrero, Mexico. Information about its distribution, ecology, conservation and morphology is provided. Phylograms are presented to clarify the relationships of this new species within Ipomoea.

Brongniartia balsensis J. Jimenez Ramirez & K. Vega (Leguminosae, Papilionoideae), a new and endemic species from the Balsas Depression, is described and illustrated. This species is similar to B. guerrerensis J. Jimenez Ramirez & J. L. Contreras, but differs from it by having a greater number of leaflets and larger pedicels, bracteoles, calyx, standard, wings, and keel; there are also differences in the form of the standard, the color of the keel (green), and the possession of a lightly winged legume.

Prockia oaxacana J. Jimenez Ramirez & Cruz Duran (Salicaceae), a new species from the Mixtec region in the state of Oaxaca, Mexico, is described and illustrated. It appears similar to P. krusei J. Jimenez Ramirez & Cruz Duran, but differs in being a polygamo-dioecious plant with exfoliating bark, stipules with marginal glands, flowers with petals, unilocular ovary, parietal placentation, and smaller sepals, berry, and seeds. A dichotomous key to distinguish this new species of Prockia P. Browne ex L. is also included.

Haematoxylum sousanum Cruz Duran & J. Jimenez Ramirez, a new species (Leguminosae, Caesalpinioideae) from the high Balsas basin from southern Mexico, is described and illustrated. It appears similar to H. brasiletto H. Karsten, but differs in presenting paripinnate or bi-imparipinnate leaves, flowers in panicles, floral parts different in form, falcate fruits, and distinct phenology.

Magnolia vazquezii Cruz Duran & K. Vega (Magnoliaceae) is described as a new species from the state of Guerrero, Mexico. It has been collected only in cloud forest in the state of Guerrero and appears similar to M. schiedeana Schlechtendal, but differs in its red stipules, pubescent bracts, pubescent and longer peduncles, longer and different-shaped petals, and an oblong gynoecium with erect stigmas. The new taxon is illustrated and a dichotomous key distinguishes it from related taxa.

Se describe e ilustra a Annona contrerasii de la sección Helogenia Saff. (Annonaceae), una especie nueva del estado de Guerrero, México. El nuevo taxon es parecido a Annona crotonifolia Mart. de Sudamérica, pero difiere de ésta por representar arbustos a árboles de mayor tamaño y tener hojas más angostas con un número mayor de venas secundarias, peciolos más cortos, tricomas simples, sépalos trulados y de menor tamaño, pétalos interiores rómbicos, estambres de menor tamaño, pistilos glabros y frutos de tamaño mayor.

Se registra por primera vez la presencia del género Ormosia para el estado de Guerrero, México, con dos especies: Ormosia carinata y O. oaxacana (Leguminosae, Papilionoideae, tribe Sophoreae). Se incluyen las descripciones de ambas, datos referentes a los ejemplares, una clave dicotómica para diferenciarlas, y la ilustración de O. carinata. Ormosia carinata era conocida como elemento endémico de los estados de Veracruz y Oaxaca, en las regiones de Los Tuxtlas y de Uxpanapa.

Jatropha spp. plants are used in traditional medicine, food and for the elaboration of biofuel. The Tehuacán-Cuicatlán Biosphere Reserve in México holds genetic richness and endemism for this genus, but the specific use of the plants and the seed chemical profiles are still unknown. The objectives of this research were to record the traditional forms of use of Jatropha species, and to analyze the chemical composition of Jatropha spp. seeds. For this, a semi-structured survey was conducted in 15 towns, and 20 interviews were applied in each one between May and August 2012. Data allowed to estimate the Significant Use Level and Relative Use Value per species. Besides, seeds from J. neopauciflora, J. rufescens, and J. rzedowskii were collected between August and October 2013, and to seed flour samples we determined total lipids by the Soxhlet method, crude protein by the Kjendahl method, and ashes according to AOAC methods; fatty acid profile and phorbol esters were determined by gas chromatography and by HPLC, respectively. We recorded that the species J. neopauciflora, J. oaxacana, J. rufescens, J. ciliata, and J. rzedowskii, are used as traditional medicine, food, and ornaments, except for J. ciliata, for which none use was recorded. The Significant Use Level as food was found not significant, but for medicinal purposes, J. neopauciflora obtained the highest Relative Use Value (9.0 %). The latex is used to treat 13 disorders, including dental problems (toothache, sensitivity, caries), oral diseases (oral herpes, gingivitis, and oral candidiasis) with a Significant Use Level of 32.9 %; it is also used as a hemostatic. The protein content among species varied from 23.37 to 26.06 %, and total lipids from 34.79 to 36.60 %. The principal unsaturated fatty acids were oleic (25.08 to 30.09 %) and linoleic (44.55 to 48.46 %), and the saturated fatty acids were palmitic (10.11 to 16.50 %) and stearic (9.47 to 11.15 %). Phorbol esters, the main cause of seed’s toxicity, were absent in J. neopauciflora, J. rufescens, and J. rzedowskii. In conclusion, the Significant Use Level of Jatropha species studied was low, with little cultural acceptance and sporadic utilization. The Relative Use Value was important for medicinal purposes, especially for J. neopauciflora. The dehulled seeds of J. neopauciflora, J. rufescens, and J. rzedowskii are potentially useful as food, having high protein contents, and unsaturated oleic and linoleic fatty acids. With this study we report three non-toxic Jatropha species and recommend to scientifically validate the antimycotic use of J. neopauciflora latex. Las plantas de las especies de Jatropha son usadas en medicina tradicional, alimento y en la elaboración de biocombustible. La Reserva de la Biosfera Tehuacán-Cuicatlán, México contiene riqueza genética y endemismo para este género, pero se desconoce el uso específico de las plantas y la composición química de la semilla. Los objetivos de esta investigación fueron: documentar las formas tradicionales de uso de las especies de Jatropha y, analizar la composición química de las semillas de las especies de Jatropha. En 15 comunidades se aplicaron 20 entrevistas semiestructuradas entre mayo y agosto de 2012 para estimar el Nivel de Uso Significativo y el Valor de Uso Relativo por especie. Se colectó semilla solo de J. neopauciflora, J. rufescens, y J. rzedowskii entre agosto y octubre de 2013 para determinar mediante los métodos de la AOAC, el contenido total de lípidos en una muestra de 3 g de harina mediante el método de Soxhlet, proteína cruda en una muestra de harina de 0.4 g por el método Kjendahl y ceniza en una muestra de 5 g de harina. El perfil de ácidos grasos se determinó por cromatografía de gases y el contenido de ésteres de forbol mediante HPLC. Las especies registradas fueron J. neopauciflora, J. oaxacana, J. rufescens, J. rzedowskii y J. ciliata, que se usan en medicina tradicional, alimento y como ornamental, excepto J. ciliata, para la cual no se reportó ningún uso. El Nivel de Uso Significativo como alimento no fue importante, pero para propósitos medicinales J. neopauciflora tuvo el mayor Valor de Uso Relativo (9.0 %). El látex es usado para tratar 13 trastornos, incluyendo problemas dentales (dolor de muelas, sensibilidad, caries), enfermedades bucales (herpes oral, gingivitis, micosis oral) con un Nivel Significativo de Uso de 32.9 %; y también es usada como hemostático. El contenido de proteína entre especies varió de 23.37 a 26.06 % y los lípidos totales variaron de 34.79 a 36.60 %. Los principales ácidos grasos insaturados fueron oleico (25.08 a 30.09 %) y linoleico (44.55 a 48.46 %); los ácidos grasos saturados fueron palmítico (10.11 a 16.50 %) y esteárico (9.47 a 11.15 %). No se detectó la presencia de ésteres de forbol (la causa principal de la toxicidad de la semilla) en J. neopauciflora, J. rufescens, y J. rzedowskii. En conclusión, el Nivel de Uso Significativo de las especies de Jatropha fue bajo, con poca aceptación cultural y utilización esporádica. El Valor de Uso Relativo fue importante para propósitos medicinales, especialmente para J. neopauciflora. Las semillas sin testa de J. neopauciflora, J. rufescens, y J. rzedowskii son potencialmente útiles como alimento por su alto contenido de proteínas, ácidos grasos insaturados oleico y linoleico. Se identificaron tres especies no toxicas de Jatropha. Se recomienda validar científicamente el uso antimicótico del látex de J. neopauciflora.

Se describe e ilustra a Recchia sessiliflora (Surianaceae Arn.), una especie nueva de la Cuenca del río Balsas en el estado de Guerrero, México. El nuevo taxon es afín a Recchia connaroides (Loes. & Soler) Standl., pero difiere de ella por tener folíolos más pequeños, que aumentan de tamaño hacia el ápice de la hoja, elípticos a suborbiculares, el raquis con alas evidentes, las inflorescencias en espiga y los pétalos oblanceolados con el ápice irregularmente emarginado. Esta especie se conoce hasta ahora solo de la localidad tipo, creciendo en bosque tropical caducifolio. Se presenta una comparación de las características de las especies afines, un mapa de distribución y una clave dicotómica para el reconocimiento de las especies conocidas del género Recchia Moc. & Sessé ex DC.

Pterostemon bravoanus sp. nov. is described from the Balsas River Basin. The species is a member of a genus so far known to encompass two species. It differs from P. mexicanus and P. rotundifolius in its larger leaves, smaller flowers and a cyme composed by more than 50 flowers.

Triumfetta acahuizotlanensis is herein described and illustrated as a new species from the state of Guerrero, Mexico. The new taxon can be identified by the presence of tetramerous flowers, four glands in the androgynophore and piriform fruit.

Se amplía la descripción de Jatropha andrieuxii Muell. Arg., incluyendo algunos datos de hábitat y una ilustración de la especie. Además, se propone su transferencia de la sección Curcas (Adans.) Griseb. a la sección Platyphyllae Dehgan et Webster por presentar corola gamopétala y estambres biseriados.

"Se presenta la riqueza florística del municipio Atenango del Río en el estado de Guerrero, México. Para ello se elaboró la lista de las especies de plantas vasculares con base en la colecta realizada durante un año en todo el municipio, así como en la revisión de material de herbario y de literatura. Los resultados muestran una cifra de 643 especies, distribuidas en 349 géneros y en 95 familias para el municipio. Las familias mejor representadas, a nivel de especie, en la zona son: Leguminosae con 96 especies, Compositae con 75, Euphorbiaceae con 42 y Graminae tiene 29. Destaca la presencia de 49 especies que restringen su distribución a la cuenca del Balsas y que están presentes en Atenango del Río."

"Se registran once especies de Jatropha en el estado de Puebla, que representan el 24% de la diversidad del género en México, todas ellas distribuidas principalmente en la cuenca del Balsas y el valle de Tehuacán- Cuicatlán, los tipos de vegetación con más especies son el bosque tropical caducifolio y el matorral xerófilo. La presencia de J. elbae J. Jiménez Ram., J. oaxacana J. Jiménez Ram. & R. Torres, J. pseudocurcas Müll. Arg. y J. websteri J. Jiménez Ram. esreportada por primera vez en el estado. Se señala la posible desaparición de dos especies endémicas de Puebla J. riojae Miranda y J. rufescens Brandegee."

A nomenclatural conflict between Quercus acutifolia and Q. conspersa is solved based on the thorough revision of herbarium specimens, type specimens, original descriptions and field observations. Q. conspersa is proposed as a synonym of Q. acutifolia , as are the names Q. acutifolia ζ conspersa , Q. acutifolia β bonplandi , Q. acutifolia γ angustifolia , Q. acutifolia e longifolia and Q. candolleana. In addition, Q. grahamii is recognized as the correct name for the taxon identified as Q. acutifolia . Q. conspersa is lectotypified and Q. conspersa f. caudata is neotypified here. Information on the distribution of Q. acutifolia and Q. grahamii and the main features used to distinguish them is also provided.

Se hizo un estudio florístico de la porción guerrerense de la Sierra de Taxco, la cual incluye un área de 730 km2 y se ubica en los municipios de Tetipac, Pilcaya, Taxco de Alarcón, Ixcateopan de Cuauhtémoc y Pedro Ascencio Alquisiras. Se generó una base de datos que contiene 4 139 registros. Se citan 1 384 especies, 570 géneros y 150 familias de plantas vasculares, así como cinco tipos de vegetación principales: bosque tropical caducifolio, bosque de Quercus (incluyendo asociaciones con coníferas), bosque de coníferas, bosque mesófilo de montaña y bosque de galería. Las familias mas representativas son Asteraceae (209 especies y 79 géneros), Fabaceae (152 y 50) y Poaceae (80 y 39).

Lacandonia schismatica is a rare flowering plant with the sex organs spatially inverted. Several aspects of its cell biology are now known. Interestingly, within the cell nucleus, the chromatin is reticulated and it is associated to a novel structure named Lacandonia granules, a very abundant ribonucleoprotein particle showing similarities to perichromatin and Balbiani ring granules, which are involved in nuclear mRNA metabolism. To see whether these particles are present in other plants, we study the nucleus of Ginkgo biloba, a non-flowering plant. Light, electron and atomic force microscopy show that the cell nuclei of G. biloba are reticulated. Ultrastructural analysis showed that in the nucleoplasm, abundant intranuclear particles 32 nm in diameter are present. The EDTA regressive staining suggested that they contain RNA. Ultrastructural in situ hybridization confirmed the presence of RNA in these particles. Therefore, we conclude that the nuclei of G. biloba are reticulated and contain Lacandonia granules. We suggest that these particles may also be present in other plants.

Se analiza la flora del municipio Eduardo Neri, en el estado de Guerrero, dentro de la cuenca del río Balsas. Se encontraron 1342 especies, 566 géneros y 134 familias en dos tipos de vegetación: bosque tropical caducifolio y bosque de Quercus, siendo el primero el de mayor distribución y el más diverso en el área de estudio. Las familias mejor representadas en la zona son Compositae, Leguminosae, Gramineae y Euphorbiaceae. Asimismo, se encontraron 29 especies endémicas para el estado de Guerrero, que crecen en este municipio.

La familia Euphorbiaceae es una de las familias mas diversas entre las angiospermas. La constituyen cinco subfamilias, 49 tribus, 317 géneros y cerca de 8100 especies, distribuidas principalmente en las zonas tropicales y subtropicales del mundo. En este trabajo se presenta la lista preliminar de géneros y especies para México, anotando la distribución y los niveles de endemismo. Se revisaron los herbarios MEXU, ENCB, FCME, UAMIZ y CHAPA, y ejemplares de CICY y CIQRO, anotando los datos disponibles. Se eliminaron los sinónimos conocidos, después de revisar bibliografía y colecciones. Se encontraron 50 géneros y 826 especies; de éstas, 55.52 % son endémicas de México. Estos números ubican a Euphorbiaceae como la sexta familia en importancia nacional, atendiendo al número de especies y la cuarta en porcentaje de endemismos. Los géneros con mayor número de especies son Euphorbia (138 spp.), Croton (126 spp.), Chamaesyce (103 spp.) y Acalypha (126 spp.). Tienen su centro de diversidad en México Bernardia, Cnidoscolus y Pedilanthus; el único considerado endémico es Enriquebeltrania. Los estados más diversos, con más de 100 especies, son en orden de importancia Oaxaca, Veracruz, Chiapas, Jalisco, Guerrero, Michoacán, Sonora, Sinaloa, Puebla, Nayarit y Tamaulipas. Se presenta una clave de identificación para los géneros de México, las descripciones y una lámina de una especie representativa del género.

La familia Euphorbiaceae es una de las familias mas diversas entre las angiospermas. La constituyen cinco subfamilias, 49 tribus, 317 géneros y cerca de 8100 especies, distribuidas principalmente en las zonas tropicales y subtropicales del mundo. En este trabajo se presenta la lista preliminar de géneros y especies para México, anotando la distribución y los niveles de endemismo. Se revisaron los herbarios MEXU, ENCB, FCME, UAMIZ y CHAPA, y ejemplares de CICY y CIQRO, anotando los datos disponibles. Se eliminaron los sinónimos conocidos, después de revisar bibliografía y colecciones. Se encontraron 50 géneros y 826 especies; de éstas, 55.52 % son endémicas de México. Estos números ubican a Euphorbiaceae como la sexta familia en importancia nacional, atendiendo al número de especies y la cuarta en porcentaje de endemismos. Los géneros con mayor número de especies son Euphorbia (138 spp.), Croton (126 spp.), Chamaesyce (103 spp.) y Acalypha (126 spp.). Tienen su centro de diversidad en México Bernardia, Cnidoscolus y Pedilanthus; el único considerado endémico es Enriquebeltrania. Los estados más diversos, con más de 100 especies, son en orden de importancia Oaxaca, Veracruz, Chiapas, Jalisco, Guerrero, Michoacán, Sonora, Sinaloa, Puebla, Nayarit y Tamaulipas. Se presenta una clave de identificación para los géneros de México, las descripciones y una lámina de una especie representativa del género.