Papers by Gabriel Sanchez-Ken
Phytotaxa
Two new records of Ehrharta erecta are formally reported from the states of Michoacán and Baja Ca... more Two new records of Ehrharta erecta are formally reported from the states of Michoacán and Baja California. This taxon is apparently a recent introduction to the Mexican flora since the dates of the specimens are from the last decade. With these records, the number of species of Flora del Bajío (Michoacán) and Baja California is increased. Based on the characteristics of the plants, the taxon growing in the Americas belongs to E. erecta var. erecta.
Revista Mexicana de Biodiversidad
Two new species of Paspalum from Mexico are described and illustrated and the identity of P. crin... more Two new species of Paspalum from Mexico are described and illustrated and the identity of P. crinitum of the group Livida is discussed. The new species, Paspalum chiapense from Chiapas and P. yecorae from Sonora, belong to subgenera Harpostachys and Paspalum group Paniculata, respectively. A preliminary account of the 88 species (including the new ones) of the genus for Mexico is presented.
Phytotaxa
The Australian species Lachnagrostis filiformis, introduced to the Americas and elsewhere in the ... more The Australian species Lachnagrostis filiformis, introduced to the Americas and elsewhere in the last century, has become a weed of temporary ponds in Mexico. Collections of several larger Mexican herbaria were consulted as well as online databases. In addition to previously reported populations from Querétaro, this species has appeared in central México in the states of Guanajuato, Michoacán, México and Puebla. In all examined specimens, most of the spikelets exhibited hairy lemmas with a long geniculate awn inserted above the mid-dorsal region, but (6.3–) 10–20 % of distal spikelets had glabrous or nearly glabrous lemmas with a partial or total suppression of the development of the awn and were slightly smaller than the spikelets with awned and hairy lemmas. All florets were assumed to be fully fertile as evidenced by the presence of empty anthers and developed caryopses.
Acta Botanica Mexicana
Antecedentes y Objetivos: En 2006 se dio a conocer el catálogo de las gramíneas de México, pero d... more Antecedentes y Objetivos: En 2006 se dio a conocer el catálogo de las gramíneas de México, pero desde entonces tanto la clasificación como la aparición de especies nuevas cambiaron las cifras de esta familia en México y en el mundo. El objetivo principal de este estudio fue actualizar la lista de taxa en México, reuniendo el mayor número posible de bases de datos en línea. Otros objetivos incluyeron la comparación de la riqueza de especies de la familia Poaceae entre los países con mayor diversidad, así como analizar la riqueza de sus taxa a nivel estatal y por categorías taxonómicas.Métodos: Se consultaron bases de datos en línea, tanto nacionales como extranjeras, que incluían ejemplares de referencia de México, se descargaron y se curaron, además de una confirmación visual de la identidad de un gran porcentaje de ejemplares. Se extrajeron los nombres de las especies, estados donde fueron colectadas y los acrónimos de los herbarios. La base resultante se complementó solo con bibli...
Phytotaxa
A new species, Dichanthelium multiglandulosum, from northwestern Jalisco, Mexico, is described an... more A new species, Dichanthelium multiglandulosum, from northwestern Jalisco, Mexico, is described and illustrated. Panicum transiens, an incorrectly synonymized name lost in history, is here proposed as D. transiens, with the rarely used name D. macrospermum treated as its synonym. Relationships of both species are discussed, and both are classified within Dichanthelium section Macrocarpa. A key and a table of differences and similarities among the new species and related species are provided.
Acta botánica Mexicana
A new species, Digitaria michoacanensis from northern Michoacán and the adjacent part of the stat... more A new species, Digitaria michoacanensis from northern Michoacán and the adjacent part of the state of México in the central-west region of Mexico, is described. Pending an updated phylogenetic infrageneric classification of the genus; the new species is placed in the group Ternata with spikelets in groups of three or more. A synopsis with a key to the Mexican species of the genus Digitaria is also provided.
Two new species of Paspalum from Mexico are described and illustrated and the identity of P. crin... more Two new species of Paspalum from Mexico are described and illustrated and the identity of P. crinitum of the group Livida is discussed. The new species, Paspalum chiapense from Chiapas and P. yecorae from Sonora, belong to subgenera Harpostachys and Paspalum group Paniculata, respectively. A preliminary account of the 88 species (including the new ones) of the genus for Mexico is presented.
Most of the available information on grass leaf anatomy comes from transverse (cross) sections. R... more Most of the available information on grass leaf anatomy comes from transverse (cross) sections. Relatively few studies have also examined grass leaves in longitudinal section, and fewer still have looked at them in paradermal view. Some work, however, including unpublished observations by Sanchez-Ken, indicates that chlorenchyma cell variation in grasses is more extensive than previously suspected. As part of a broad survey of chlorenchyma cell structure and evolution in the Poaceae, we report the results of our initial 3-D reconstruction of chlorenchyma cells in Oplismenus hirtellus, a broad-leaved, C3 grass that represents the "forest shade" clade (subtribe Boivinellinae) within the diverse tribe Paniceae. In this species, chlorenchyma cells adjacent to the bundles are cylindrical and elongated and more or less radiate, curving toward the adaxial epidermis. Chlorenchyma cells in the intercostal zone or adjacent to the abaxial epidermis below the bundles are mostly more o...
Listado de las malezas gramíneas nativas e introducidas en México, su distribución general en el ... more Listado de las malezas gramíneas nativas e introducidas en México, su distribución general en el país, usos o importancia
Tratamiento taxónomico de la subfamilia Panicoideae de la Flora del Valle de Tehuacán-Cuicatlán, ... more Tratamiento taxónomico de la subfamilia Panicoideae de la Flora del Valle de Tehuacán-Cuicatlán, ubicada al sur de Puebla y norte de Oaxaca, Mexico.
Las Poaceae, una familia de gran importancia económica y ecológica, incluye aproximadamente 700 g... more Las Poaceae, una familia de gran importancia económica y ecológica, incluye aproximadamente 700 géneros y 8,000 a 10,000 especies. Adaptaciones importantes para el éxito evolucionario de las gramíneas incluyen la construcción modular de las plantas, dispersión de diásporas, el meristemo intercalar, y la presencia de fotosíntesis C4. Los últimos análisis filogenéticos de la familia muestran que varios grupos de gramíneas herbáceas anteriormente clasificados como bambúes formas las líneas basales. La familia probablemente se originó en los bosques del hemisferio sur, y se diversificó ampliamente en el Oligoceno y el Mioceno. Se discute la evolución de las líneas y sus adaptaciones basadas en la filogenia.
Kew Bulletin
Two new species of grasses from Tanzania, Eragrostis uzondoiensis Sánchez-Ken and Brachiaria uzon... more Two new species of grasses from Tanzania, Eragrostis uzondoiensis Sánchez-Ken and Brachiaria uzondoiensis Sánchez-Ken are described and illustrated.
Journal of Vegetation Science, 2015
ABSTRACT Niche differentiation may promote species co‐existence because it precludes competitive ... more ABSTRACT Niche differentiation may promote species co‐existence because it precludes competitive exclusion. However, in stressful environments, facilitation may predominate, and large niche overlaps may result from niche widening and positive spatial associations. We analysed the niche structure of a species‐rich system over a soil depth gradient (a niche axis positively correlated with water availability) and tested for various patterns expected from competition or facilitation. Stable coexistence requires differentiation between species. We report evidence for niche differentiation along a soil depth gradient related to hydrology. Niche overlap was small, niches became narrower in the presence of competitors, and community structure changed over the gradient. This is consistent with competition, but not facilitation, as a driver of community structure, suggesting that hydrology is critical for coexistence (Photo: F. Pedraza).
Invasive Plant Science and Management, 2014
Hyparrhenia cymbaria (boat thatching grass, ipopo grass) and Hyparrhenia variabilis (no common na... more Hyparrhenia cymbaria (boat thatching grass, ipopo grass) and Hyparrhenia variabilis (no common name), robust African savanna grasses with complex taxonomies, have not yet been reported for the Americas. Large populations were found in central Jalisco, northeastern Michoacán, and Morelos, Mexico. The species grow in maize and sorghum fields as well as on roadsides and in old fields, but always in association with present or past sorghum cultivation; this suggests introduction through contaminated seed material from Africa. Because of the size and density of the populations, and their native ecology, they are both agricultural pests as well as a potentially dangerous invaders for the American (sub)tropical grasslands and native scrublands, including the southern United States. The invasion underlines the importance of effective phytosanitary controls of the seed supply.
Illustrated Handbook of Succulent Plants: Monocotyledons, 2001
Annals of the Missouri Botanical Garden, 1995
Chromosome counts are reported as follows: Aristida adscensionis 2n= 22, A. divaricata 2n= 22, A.... more Chromosome counts are reported as follows: Aristida adscensionis 2n= 22, A. divaricata 2n= 22, A. glauca n= 22 and 2n= 44, A. laxa 2n= 44, A. schiedeana 2n= 22, 44, and A. ternipes 2n= 22. The reports of 2n= 22, 44 chromosome numbers for A. curvifolia and n= 11 and 2n ...
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Papers by Gabriel Sanchez-Ken