Showing papers in "Boletin De La Sociedad Botanica De Mexico in 2017"
TL;DR: A preliminary list of 161 species from the genus Quercus, all native to Mexico, is presented in this article, which belongs to three sections: section Lobatae (red oaks, 76 species), quercus (white oak, 81 species), and Protobalanus (intermediate oak, 4 species).
Abstract: This study presents a preliminary list of 161 species from the genus Quercus, all native to Mexico. These species belong to three sections: section Lobatae (red oaks, 76 species), Quercus (white oaks, 81 species), and Protobalanus (intermediate oaks, 4 species). It is estimated that 109 are endemic to Mexico, 47 of which belong to section Quercus, 61 to section Lobatae, and 1 to section Protobalanus. Of all the oak species found in Mexico, 33 of them extend their range into the United States, while only 20 are also found in Central America. The states with the greatest oak divesity are Oaxaca, Nuevo Leon, Jalisco, Chihuahua and Veracruz. Species widely distributed in Mexico are Q. candicans, Q. castanea, Q. crassifolia, Q. laeta, Q. microphylla, Q. obtusata and Q. rugosa. In general, Mexican oak species grow in elevations ranging form 0 to 3,500 m; however, they are found predominantly between 1,000 and 3,000 m. Knowledge on the taxonomy of Mexican oak species remains incomplete; therefore, further research is needed around this important genus.
213 citations
170 citations
TL;DR: An updated account of the generic richness of Mexican vascular plants records 2,804 native genera, distributed in 304 families, including the largest number (2,663 genera), 2,117 of them dicotyledons (Magnoliophyta) and 546 monocotylingons (Liliopsida).
Abstract: An updated account of the generic richness of Mexican vascular plants records 2,804 native genera, distributed in 304 families. The flowering plants include the largest number (2,663 genera), 2,117 of them dicotyledons (Magnoliophyta) and 546 monocotyledons (Liliopsida). In addition, 127 genera of ferns and fern allies and 14 of gymnosperms are recorded. A list of gener- ic names is provided, as well as a brief discussion about their richness patterns and their geographical and ecological distribution. Of the total generic richness of Mexico, 7.8% (219 genera) is considered to be endemic to this country.
112 citations
TL;DR: The plant associations of the phytogeographic province of Tehuacan-Cuicatlan Valley are described and classified according to the species dominance and physiognomy based on field samplings of 500 m2 as mentioned in this paper.
Abstract: The plant associations of the phytogeographic province of Tehuacan-Cuicatlan Valley are described and classified according to the species dominance and physiognomy based on field samplings of 500 m2. The altitudinal distribution of the associations was determined conducting 250 m2 samplings located every 100 m altitude in throughout five environmental gradients. A total of 29 plant associations were recognized including nine associations dominated by columnar cacti, four types of deciduous forests, three types of Izotal, and six type of shrublands. Mountainous arboreal vegetation includes five types of forests, as well as a Mountainous lzotal. The vegetation associated to aquatic environments along rivers and springs include Galery forests and "Tulares". The pronounced heterogeneity of Tehuacan-Cuicatlan Valley determines the diversity and the distribution of the vegetation associations.
110 citations
109 citations
TL;DR: A model of domestication of plants in Meso-america based on selective management of plant populations and communities by silvicultural practices is analyzed in this paper, where the authors suggest that intentional manipulation of vegetation by Mesoamerican peoples has occurred in past and present times in order to control availability of useful plants.
Abstract: A model of domestication of plants in Mesoamerica based on selective management of plant populations and communities by silvicultural practices is analyzed. Archaeological and ethnobotanical information suggests that intentional manipulation of vegetation by Mesoamerican peoples has occurred in past and present times in order to control availability of useful plants. Forms of management of plant communities or populations have included tolerance, protection and enhancement of individual plants of particular species during clearance of vegetation and other ways of perturbation. Processes of artificial selection (selection in situ) may be carried out through these forms of plant management. These processes may cause significant morphological differences between wild and managed populations as illustrated by the cases discussed here of Anoda cristata, Crotalaria pumila, Leucaena esculenta and Stenocereus stellatus. Processes of artificial selection in situ are mechanisms of incipient domestication of plants which appear to have been carried out in Mesoamerica, perhaps since pre-agricultural times, and that could contribute to explain the processes that led to the origins of agriculture in this region.
106 citations
TL;DR: In this article, the authors provide the classification, description and spatial distribution of the plant communities of the Calakmul region, at the center of the Yucatan peninsula, containing the largest forested area of the Mexican tropics.
Abstract: The Calakmul region, at the center of the Yucatan peninsula, contains the largest forested area of the Mexican tropics. Our objective is to provide the classification, description and spatial distribution of the plant communities of Calakmul region. In spite of the relatively lack of topographic features there is large spatial heterogeneity in the vegetation. Five plant associations are underlined because of their regional, national and world relevance: guayacan forest (Guaiacum sanctum), jobillo forest (Astronium graveolens), low deciduous forest, tall forest and mixed seasonally flooded forest. We discuss the main factors influencing the vegetation, including rainfall gradients, soil development, natural disturbances and anthropogenic factors. This study underscores the importance of using vegetation classification with enough detail to assess the representation and effectiveness of natural protected areas.
87 citations
66 citations
TL;DR: In this paper, the authors developed a conceptual framework which considers the level of propagule availability of native species and the degree of environmental alteration (site quality) as two major determinants of the regeneration capacity of rain forest vegetation in abandoned fields.
Abstract: Tropical rain forests have suffered intense deforestation and degradation due to anthropogenic activities. Areas once occupied by these highly diverse forests are now conformed by mosaics of agricultural fields, secondary forests, and, to a lesser extent, primary forest remnants. To study tropical rain forest succession and restoration ecology in the extensive abandoned deforested fields, the classic gap regeneration theory proves to be insufficient. These scenarios demand ecological principles that allow the development of efficient technologies for rainforest restoration in highly disturbed abandoned fields. The present paper develops a conceptual framework which considers the level of propagule availability of native species and the degree of environmental alteration (site quality) as two major determinants of the regeneration capacity of rain forest vegetation in abandoned fields. Land use history is a major promoter of the status of these two axes as it inflicts disturbances of certain intensity, extent, and duration on propagule availability and environmental conditions. We identify key ecological factors which should be considered in the restoration of degraded fields. According to our model, the rate and magnitude of natural regeneration (regeneration capacity) decrease as propagule (i.e. seed bank and seed rain, advanced regeneration, meristems in roots and stems) availability and site quality (i.e. soil compaction and fertility, exotic vegetation abundance) decline. Different land use types have varying negative effects on the regeneration capacity of native vegetation. For example, we predict that regeneration capacity should be higher in abandoned milpas (which alter in a muchlesser degree propagule availability and site quality) than at abandoned cattle raising pastures. Predictions are evaluated through a literature review, and from a long-term research project which took place in the Selva Lacandona region (Chiapas), Mexico. Finally, restoration costs and possible recommendations that could promote ecological succession in degraded fields are presented and discussed
60 citations
TL;DR: This paper reconstructed the Agavaceae family phylogeny using ITS l and ITS 2 data, and calibrated a molecular clock to discuss the evolutionary patterns in the family, mapping the different characters in the phylogeny.
Abstract: The Agavaceae family comprises eight genera with contrasting reproductive biologies, given that they can be iteroparous (if they can reproduce several times), or semelparous ( if each individual produces an inflorescence and then dies); they also display a wide variety of floral morphologies and of pollinators (from bees to bats, including hummingbirds and moths). Here we review their reproductive biology and attempt a synthesis of their population genetics and evolution. In order to do these analyses, we reconstructed their phylogeny using ITS l and ITS 2 data, and calibrated a molecular clock. We use Hasta for comparisons, although we review some genera that have been considered related to the family. To close the paper, we discuss the evolutionary patterns in the family, mapping the different characters in the phylogeny.
56 citations
TL;DR: The Tehuacan-Cuicatlan Valley Floristic Povince covers an area of approximately 10,000 km-, with ca. 630 genera and 1,400 species of vascular plants as discussed by the authors.
Abstract: The Tehuacan-Cuicatlan Valley Floristic Povince covers an area of approximately 10,000 km- , with ca. 630 genera and 1,400 species of vascular plants (Davila, 1983). Its climate is predominantly semiarid and its endemic flora is notably rich. The generic flora is analyzed from the viewpoint of its geographic and climatic affinities, as well as its floristic relationships with other geographical regions. The tropical affinities, particularly the neotropical ones, of this generic flora , prevail over all others: the characteristically Mexican element being second in importance. The floristic relationships with other geographical regions are significant, pointing to a strong correspondence with most of them, especially with those with a xerophytic vegetation, showing also a stronger floristic resemblance to some South American regions than with western North America. All of this places the Tehuacan-Cuicatlan Valley in a strategic phytogeographic position, where the commingling of the typically tropical component with that which is characteristic of more northern arid zones can be best observed, which accounts for the great floristic richness found in such a small area.
TL;DR: The distribution of the Agavaceae and Nolinaceae families in the Americas and in Mexico is analyzed in this paper. But the authors focus on the distribution of taxa from the Agave family in Mexico.
Abstract: We show the distribution of the Agavaceae and Nolinaceae families in the Americas and in Mexico. For Mexico we determined the existence of 402 taxa of which 342 belong to the genera Agave, Beschorneria, Furcraea, Hesperaloii, Manfreda, Polianthes, Prochnyanthes and Yucca in the Agavaceae family, while 60 are from the genera Beaucarnea, Calibanus, Dasylirion and Nolina from the Nolinaceae family. We also show an updated list of the species from both families arranged alphabetically. For each taxon we describe their distribution by state and by floristic provinces. The richest states are Oaxaca with 63 taxa, Durango with 52, Puebla with 50, San Luis Potosi and Sonora with 47 and Chihuahua with 45. The floristic provinces with higher number of taxa are: The Meridional Sierras, the Sierra Madre Occidental and the Central Mexico Highlands. At the moment,' for Mexico, five regional floras have been finished that study the Agavaceae and Nolinaceae at different levels. The genera Agave, Beaucarnea, Beschorneria, Manfreda and Prochnyan.thes have had recent taxonomic treatments; others like Dasylirion, Furcraea and Polianthes are in different stages of development, while Calibanus, Hesperaloii, Nolina, Yucca and several groups of Agave require an update. We review data on the representation of the taxa in two of the main herbaria in Mexico (ENCB and MEXU), which comprise 220 species, backed by 3,593 vouchers, with an average of 16.3 vouchers per taxon. Nevertheless it is necessary to increase the collection for herbarium and botanical gardens, to not only to back up floristic and taxonomic research, but also to support research in ecology, ethnobotany, conservation biology, etc. These actions will allow us to have a better knowledge of the biology of the Agavaceae and Nolinaceae.
TL;DR: In the central area of Veracruz a few remnants of cloud forest have not been explored previously and the ftoristic composition and some structural features of one of these remnants of CF in La Cortadura are studied.
Abstract: In the central area of Veracruz a few remnants of cloud forest (CF) have not been explored previously. We studied the ftoristic composition and some structural features of one of these remnants of CF in La Cortadura. Sampling of woody plants, herbs and
TL;DR: A review of plant population ecology studies that have done in Mexican tropical rain forests, particularly at the Los Tuxtlas Tropical Field Station (UNAM), is presented in this paper.
Abstract: This paper reviewing plant population ecology studies that have done in Mexican tropical rain forests, particularly at the Los Tuxtlas Tropical Field Station (UNAM). The review considers next topics: (i) population structure and demographic patterns, (ii) population dynamics, (iii) life-history evolution, and (iv) the importance of demography and genetics for conservation and management of tropical rain forest plant products. The studies show an important advance in the description of patterns, in the analysis of population dynamics, and in the detection of some key demographic elements that can be important for forest conservation and management. However, the understanding of causes that originate such patterns and dynamics is yet poor. The studies have focused mainly on abundant arboreal plant species; other plant life-forms and rare species have received virtually null attention. After pointing out conclusions gained from our review, we propose some perspectives for future research.
TL;DR: This review presents methodological, evolutionary, ecological, and physiological aspects on CAM plants, and shows data from recent studies related to the environmental effect on changes in the photosynthesis CAM.
Abstract: Mexico possesses a great species diversity of Crassulacean Acid Metabolism (CAM) plants. These plants can grow in places where water is infrequent, such as arid and semi-arid zones, and tree canopies, or as aquatic plants in places with low CO2 availability. This review presents methodological, evolutionary, ecological, and physiological aspects on CAM plants. Also, it shows data from recent studies related to the environmental effect on changes in the photosynthesis CAM. Finally, we made a consideration about the lack of studies on the physiology of CAM plants in Mexico despite its enormous diversity.
TL;DR: The biogeographic and archeobotanical studies indicate that during the dispersion of Capsicum along the American Continent, some of the species were domesticated independently in different places: C. annuum, C. chinense, and C. frutescens are taxa that form a taxonomic complex that can be barely differentiated and at the present it is impossible to determine whether they belong to the same or different species.
Abstract: The genus Capsicum consists of approximately 30 species of which C. annuum, C. chinense, C. frutescens, C. baccatum and C. pubescens are domesticated. Although Capsicum has been studied from the taxonomic and evolutionary point of view, using morphological, cytological and molecular characters, there are still sorne problems related to the taxonomic delimitation of the genus and its species, the nomenclature of the wild and cultivated forms, and the treatment of infraspecific variation. In order to determine the generic and specific taxonomic limits and to establish their phylogenetic and evolutionary relationships, it is necessary to undertake these studies among all the taxa of the genus Capsicum. C. annuum, C. chinense, and C. frutescens are taxa that form a taxonomic complex that can be barely differentiated and at the present it is impossible to determine whether they belong to the same or different species. The center of origin of the genus Capsicum is in South America, in the region that comprises Bolivia, northern Argentina, and central and southern Brazil. The biogeographic and archeobotanical studies indicate that during the dispersion of Capsicum along the American Continent, some of the species were domesticated independently in different places: C. annuum in Mexico; C. frutescens in Costa Rica, and possibly also in Mexico; C: chinense in the Amazonas lowlands; C. baccaturn in Bolivia, and C. pubescens in the Andes. In Mexico, C. annuwn has been cultivated throughout all the country; C. frutescens in the central and south eastern regions; C. chinense in the Yucatan Peninsula, and C. pubescens in the high lands of the central states. In addition, there are C. ciliatum and C. lanceolatum, two species that have never been used by man. Genetic and ecological studies on wild populations are very important for the use and conservation of this genetic resource.
TL;DR: Although canopy structure and tree species diversity varied continuously across the landscape, -diversity (evaluated through species similarity between plot pairs and the identities of dominant species exhibited the clearest distinction.
Abstract: Landscape level variability of structure and tree species diversity was analyzed in a tropical deciduous forest at Chamela, Mexico. Trees with DBH ≥5 cm were sampled in 21 0.24 ha plots (5.04 ha in total) distributed among six different morpho-pedological land units. Average density was 1,385 individuals ha-1, basal area 15.9 m2 ha-1, and canopy height 6.8 m. Trunks with DBH ≤14 cm accounted for 90% of the entire set. A total of 148 species, 102 genera, and 43 families were recorded. Seventy percent of all species were poorly represented (< 10 individuals ha-1). A Principal Component Analysis (PCA) based on structure and diversity variables showed that plots from the same morpho-pedological land unit were not always located close to each other along the two first axes, but a further PCA based on dominant species clearly divided two groups of plots. Although canopy structure and tree species diversity varied continuously across the landscape, -diversity (evaluated through species similarity between plot pairs) and the identities of dominant species exhibited the clearest distinction. The dichotomy between granitic vs. non-granitic lithology was the condition most clearly related with a lower similarity in species composition and the strongest contrast in the dominant species group.
TL;DR: Tropical dry forest structure at Cerro Verde is comparable to other Mexican communities within the seasonally dry tropical region and indicates a good conservation status, which makes this area a high priority site which requires inclusion in a formal conservation scheme.
Abstract: In this study we describe the structure, floristic composition, and diversity of the tropical dry forest established on the Cerro Verde (Verde Hill), located at Nizanda (Isthmus of Tehuantepec, Oaxaca, Mexico). We censused woody plants with DBH Ɛ 1 cm (upper stratum) present in 30 100-m2 plots, and in five 4-m2 subplots within each of them, those plants with height > 30 cm but < 1 cm DBH (lower stratum). A total of 194 species belonging to 52 families were recorded. Species richness was identical in both strata (145 species), each contributing exclusively with ca. 25% of total recorded richness. Leguminosae was the most speciose family (27), followed by Asteraceae (20) and Euphorbiaceae (18). The most frequent species were Bursera simaruba + B. aff. cinerea (not distinguished in the field), Euphorbia schlechtendalii, Pilosocereus collinsii and Capparis verrucosa. Average richness by plot was 30 species. Mean values of indices based on species richness and abundances (Berger-Parker = 0.20; Simpson = 0.09; Fisher’s[= 9.47; Shannon = 2.78; eveness = 0.82) indicated a high diversity and consequently a low dominance in this forest. Extrapolated values showed a total (upper + lower strata) density of 23,950 ind. ha-1 (830 ind. ha-1 with DBH Ɛ 10 cm), a forest cover of 446.7%, and a basal area of 53 m2 ha-1. Mean height of those individuals accounting for 10% of the highest trees by plot was 9.1 m. Tropical dry forest structure at Cerro Verde is comparable to other Mexican communities within the seasonally dry tropical region and indicates a good conservation status. This feature, together with its particular floristic composition, makes of this area a high priority site which requires inclusion in a formal conservation scheme.
TL;DR: A list of 3,400 species of vascular plants from the Lacandona region in Chiapas, Mexico is presented in this article, which comprises 78.8% of the total of species estimated for the region.
Abstract: A list of 3,400 species of vascular plants from the Lacandona region in Chiapas, Mexico, is presented. This number comprises 78.8% of the total of species of vascular plants estimated for the region. The data were obtained from the identified material collected by the first author, from herbarium specimens, and from bibliographic sources. Some taxa not previously recorded for the region are pointed out, and the most common synonyms are included. A delimitation and geographic description of the region are provided, as well as some data on the vegetation and the explorations carried out therein.
TL;DR: A review based on literature and herbarium voucher information on the non-wood uses of oaks in Mexico is presented in this paper, where five different uses were recorded: (1) medicinal, related mainly to digestive apparatus sicknesses: (2) food, including consumption of different structures, both fresh and processed; (3) handcraft, to elaborate different manufactured crafts, like rosaries and toys; (4) fodder, for goats and pigs; (5) tannins and dyes, to turning raw skins into leather and to act like mordant
Abstract: A review based on literature and herbarium voucher information on the non-wood uses of oaks in Mexico is presented. Fifty-five species of Quercus are gathered and used for different purposes, mainly in those states located in the central and south regions of the country. No relationship was found between species diversity by state and number of useful species. Five different uses were recorded: (1) medicinal, related mainly to digestive apparatus sicknesses: (2) food, including consumption of different structures, both fresh and processed; (3) handcraft, to elaborate different manufactured crafts, like rosaries and toys; (4) fodder, for goats and pigs; (5) tannins and dyes, to turning raw skins into leather and to act like mordant and to dye fibers. There is a relationship between the presence of ethnic groups and the use of the oaks in a given region, indicating the cultural value of these species in addition of their importance as a complementary plant resource.
TL;DR: Floristic data based on 8,063 original botanical collections make the Zimatan region of Oaxaca one of the most comprehensively collected areas and most diverse on the Mexican Pacific coast, along with the Chamela Biological Station in Jalisco State.
Abstract: The Zimatan region of Oaxaca is characterized by the occurrence of several vegetation types and a large floristic diversity, primarily due to the large elevational range that it encompasses (from sea level to 2,580 m). In 1991 this region was proposed as a high-priority area for conservation in Oaxaca State, largely due to its extensive, well-preserved tracts of tropical dry forest. Nonetheless, little biological information is available for this area. In 1997 we initiated a series of studies aimed at supporting the conservation of the Zimatan region. Here we present floristic data based on 8,063 original botanical collections. The list includes 1,384 vascular plant species, distributed among 668 genera and 144 families. These collections make of the Zimatan region one of the most comprehensively collected areas and most diverse on the Mexican Pacific coast, along with the Chamela Biological Station in Jalisco State.
TL;DR: In this paper, a review of various methods for germination analysis is presented, divided in graphical and analytical (Indices and curve fitting to logistic and normal distribution functions) and illustrated with the Manfreda brachystachya germination data in a temperature gradient.
Abstract: Methods for germination analysis were reviewed in this work. These methods were divided in graphical and analytical (Indices and curve fitting to logistic and normal distribution functions). Each one was illustrated with the Manfreda brachystachya germination data in a temperature gradient. Germination parameters were underlined: capacity and rate germination, mean time, and variance in mean time germination. These parameters must be measured accurately. The advantages and disadvantages of the different methods are discussed. Indices which try to relate germination capacity with time are not recommended to obtain relative values of germination rate, because they confound the effects that can have the different parameters. The use of logistic and normal functions are recommended, because they are models that analyze germination behavior in time and provide the values of the main germination parameters.
TL;DR: In this article, the use of topographic information for selecting the mangrove species to be used in reforestation of altered mangroves and in recently created artificial habitats is demonstrated.
Abstract: Coastal wetlands are composed of several communities located along topographic gradients, where variations in salinity and flooding result in different floristic compositions and dynamics. The topographic profile in the wetlands north of La Mancha Lagoon, Veracruz, Mexico, exemplifies this variety. The temporality and intensity of tides and freshwater fluxes, or a raise in the water table, determine the hidroperiod, defining the salinity and the soil redox conditions, thus characterizing the type of wetland. Restoration practices should take microtopography as well as the resulting hidroperiod into account. The use of topographic information for selecting the mangrove species to be used in reforestation of altered mangroves and in recently created artificial habitats, is demonstrated here. The relevance of the hidroperiod for the establishment of freshwater native species is also shown, as well as how its modification favors the entry and dominance of invasive species
TL;DR: A review of floristic and taxonomic literature, as well as on the examination of specimens housed at the herbaria of the Centro Regional del Bajio (IEB) and the Instituto de Biologia (MEXU) was conducted in this paper.
Abstract: Based on the review of floristic and taxonomic literature, as well as on the examination of specimens housed at the herbaria of the Centro Regional del Bajio (IEB) and the Instituto de Biologia (MEXU), we recorded 845 species, 352 genera and 100 families of trees for the state of Michoacan, Mexico. The largest numbers of species per family were recorded for Asteraceae (82), Fabaceae (74), Mimosaceae (67), Caesalpiniaceae (39) and Burseraceae (38), while at the genus level Bursera (37), Quercus (35), Lonchocarpus (19), Senna (18), and Acacia (16) are the most speciose. The genus Beiselia (Burseraceae) and 14 species (1.8 %) are strict endemics to the state. A total of 28 families (28%) and 210 genera (60%) are represented in the state only by one tree species each. The most important vegetation types according to their species richness are tropical deciduous forest (593, 70.2%), coniferous forest (336, 39.8%) and oak forest (332, 39.3%). A high proportion (69.9%) of Michoacan’s tree species is located in 2-4 vegetation types; 173 species (21.5%) have been found just in one type, mainly in the tropical dry forest (87 species, 10.3%). The floristic richness of Michoacan is largely explained by its complex geologic history, its rugged physiography, its diverse climate, and its multiple vegetation types, as well as by its location at the confluence of the Holartic and Neotropical floristic kingdoms. Counties and species on which to focus conservation efforts for trees in the state are pinponted.
TL;DR: In this paper, the authors describe the different plant communities along an altitudinal gradient between 1350 to 1700 meters above the sea level, in the vicinities of the Cerro Cuta, emphasizing on the differential species distribution among communities (β diversity).
Abstract: The Zapotitlan de las Salinas Valley located in the South Western portion of the Tehuacan-Cuicatlan Valley, harbors a high plant diversity with a high proportion of endemism. In this study we describe the different plant communities along an altitudinal gradient between 1350 to 1700 meters above the sea level, in the vicinities of the Cerro Cuta, emphasizing on the differential species distribution among communities (β diversity). The plant communities description was conducted considering the different geomorphic surfaces (slopes with different Iithologies, altitudes and aspects, alluvial deposits along the Salado River and flat zones on the top of hills) and they were described by means of field samplings analyzing their structure and composition . The vegetation-type diversity is associated to soil and lithological heterogeneity in the study site producing a mosaic of plant communities in which a total species turnover of 71.3% indicates a high number of species restricted to different vegetation types. This high β diversity contributes to the high regional diversity (y-diversity) reported for the Zapotitlan Valley.
TL;DR: A survey of the diversity, distribution, and conservation status of the family Lauraceae in southern Mexico found the states of Chiapas, Oaxaca, and Veracruz have the largest numbers of species, particularly for the cloud forest and the tropical rain forest.
Abstract: A survey of the diversity, distribution, and conservation status of the family Lauraceae in southern Mexico was conducted. The diversity account resulted in a list of 120 species representing 10 genera: Aiouea, Beilschmiedia, Cassytha, Cinnamomum, Licaria, Litsea, Mocinnodaphne, Nectandra, Ocotea and Persea. The states of Chiapas, Oaxaca, and Veracruz have the largest numbers of species, particularly for the cloud forest and the tropical rain forest. Endemic species account for 47.5% of the surveyed taxa, which concentrate in Chiapas, Oaxaca, and Veracruz. Only 58 of the species considered in the study are present in the system of nature reserves in southern Mexico. The general implications of these findings for the persistence of this component of the Mexican flora are discussed.
TL;DR: Wild relatives of pepper maintain high levels of variability of genetic, morphological and germination capacity, and they have potentially useful genes; they are valuable genetic resources that the authors need to study and to preserve.
Abstract: Results of studies on variation of genetic, morphological, germination and resistance to PHV (pepper huasteco virus) geminivirus of wild populations of C. annuum collected in Sinaloa state are presented in order to show the importance of studing the wild relatives of cultivated plants. The study on resistance to PHV geminivirus with the biolistic method showed high variability between populations in this trait. Sorne populations showed low levels of disease symptoms, and they are very promising for further studies on virus resistance. The isozymes study showed that ali the populations maintain high genetic variability (heterozygosity ranged between 0.255 to 0.325). Ali the wild C. annuum populations showed high variability in ten of eleven morphological traits analyzed. Most of the germination tests showed a great variability in response among the populations studied. Ali the wild C. annuum populations did not germinate under dark conditions, suggesting the existence of seed dormancy. In conclusion, wild relatives of pepper maintain high levels of variability of genetic, morphological and germination capacity, and they have potentially useful genes; they are valuable genetic resources that we need to study and to preserve.
TL;DR: In this article, an updated list of the native species of trees of the Mexican portion of the Yucatan Peninsula is provided (Campeche, Quintana Roo, y yucatan) for each species the state(s) in which it occurs is cited.
Abstract: Based on exhaustive studies of herbarium specimens held at the National Herbarium of Mexico (MEXU), as well as of the literature, an updated list of the native species of trees of the Mexican portion of the Yucatan Peninsula is provided (Campeche, Quintana Roo y Yucatan). For each species the state(s) in which it occurs is cited. The list includes 437 species belonging to 246 genera and 68 families. An appendix listing 376 excluded species, including 68 of dubious occurrence in the peninsula is provided, clarifying the reason for their exclusion as members of the flora of the Peninsula. The richest families are Mimosaceae, Euphorbiaceae, Fabaceae, Rubiaceae, and Myrtaceae; the richest genera are Acacia, Eugenia, Coccoloba, Croton and Lonchocarpus. The percentage of endemism is around 12.3% (54 taxa in 26 families); the families with more endemic species are Cactaceae, Fabaceae, Mimosaceae, Polygonaceae and Rubiaceae. At the state level, Quintana Roo harbors the most species (351). The use of five different similarity coefficients (Braun-Blanquet, Dice, Drive & Kroeber, Jaccard and Simpson) to analyze both the total number of species and the endemic ones, supports the idea of considering the states as part of the same floristic province. Finally, the need to intensify the floristic and taxonomic work, aimed at evaluating in the near future more properly the floristic richness in the Peninsula is pointed out. This will allow a more precise definition of its floristic subdivisions, its degree of endemism and its floristic relationships with neighbouring regions.
TL;DR: A floristic inventory of a mesophylous montane forest was made in the region of Teocelo, Veracruz, Mexico as discussed by the authors, taking into account only the distributional area of the genera (pantropical, neotropical, tropical asiatic, tropical african, holarctic and cosmopolitan).
Abstract: A floristic inventory of a mesophylous montane forest was made in the region of Teocelo, Ver. A floristic list of the vascular flora, consisting of eighty four families, one hundred and seventy six genera and two hundred and seventy seven species are included. Taking into account only the distributional area of the genera (pantropical, neotropical, tropical asiatic, tropical african, holarctic and cosmopolitan), six floristic geographic elements were identified. At the genus level, the tropical element proportionally attains the highest values (79%). The similarity index between Teocelo and other Mexican states shows that in terms of the mesophylous montane forest, it is more similar to the neighbouring areas of Veracruz and Chiapas. The percentage of genera in common with five typical localities was determined using the Sorensen Index, indicating that it is more similar to some areas of Guerrero. In conclusion, the proportions of the different geographic elements within the Mexican mesophylous forests, are due to the forests' complex and long Tertiary and Quaternary history. Their study is most urgent today, due to their rapid degradation and diminishing area caused by human impact.
TL;DR: Germination response and seedling growth of Mammillaria magnimamma were analyzed and seedlings are slow growing and respond positively to an increase in nutrient availability and light intensity.
Abstract: Germination response and seedling growth of Mammillaria magnimamma were analyzed. Germination percentage and germination velocity of seeds under different conditions were quantified. Treatments included light/ dark conditions, acidity pretreatments and different temperatures. Seeds are photoblastic positive and show a high viability (86%); light requirement decreases as seeds age. Different temperatures during germination resulted in different germination velocities. Pretreatments with chlorhidric acid did not affect seed viability. Seedling growth in greenhouse conditions was studied using a factorial design which included two levels of light intensity, two levels of nutrient availability and two levels of watering frequency. Seedlings are slow growing (between 0.014 and 0.027 g g-1 d-1) and respond positively to an increase in nutrient availability and light intensity.