Search

—The number and identity of species within Euthamia (Asteraceae, Astereae) have varied considerably among taxonomic treatments. Euthamia graminifolia (L.) Nutt. is often treated broadly, including plants from the northern and eastern United States and Canada, including the Atlantic and Gulf Coasts. Broad-leaved, largely glabrous plants from New Jersey to the Florida Panhandle have been inconsistently treated as E. graminifolia, E. graminifolia var. hirtipes (Fernald) C.E.S. Taylor & R.J. Taylor, E. hirtipes (Fernald) Sieren, or a hybrid between E graminifolia and E. caroliniana (L.) Greene ex Porter & Britton. Similarly, plants from the Florida Panhandle to eastern Louisiana have been incorporated into E. graminifolia or E. graminifolia var. hirtipes with only Greene in 1902 recognizing these plants as a distinct species, E. scabra Greene. To determine the identity and proper rank of these entities, morphological and phylogenetic analyses were performed to evaluate relationships within Euthamia. Plants from the Atlantic Coast most morphologically resemble Gulf Coast plants which similarly resemble E. gymnospermoides Greene. The Gulf Coast plants and E. gymnospermoides share similar DNA sequences while the Atlantic Coast plants represent a unique clade. Neither Gulf Coast nor Atlantic Coast plants contain highly polymorphic sequences, indicating that they are not hybrids. Occasional plants found within southernmost Alabama and the Florida Panhandle have polymorphic sequences and intermediate morphology however, suggesting that putative hybrids exist between Gulf and Atlantic Coast plants. This study concludes that both entities deserve specific rank as E. scabra Greene for scabrous plants along the central Gulf Coast and E. hirtipes (Fernald) Sieren for largely glabrous plants mostly along the Atlantic Coast. Ecological niche modeling indicates that precipitation, especially during summer months, and soils, namely coarse fragments and sand content, drive the distribution of these organisms, largely restricted to either side of the Apalachicola River serving as a distributional barrier.

Background and aims Cyperus is a large, ecologically diverse, and important sedge genus. Recent systematic work resolved problems with generic delimitation and implicated C4 photosynthesis as a possi

Acer binzayedii, a new species of Sapindaceae from cloud and high elevation forests in Jalisco State, Mexico, is described and illustrated. Acer binzayedii is characterized by deeply sagittate anther bases bearing scattered trichomes, the wing sulcus covering more than half of the nutlet, sparsely distributed coalescent and anastomose veins of the wings with reticulate veinlets sometimes present, trichomes on the abaxial leaf surfaces with short nodulations of reduced prominence, conical buds, and grey bark with long vertical ridges. The new species is compared to putative relatives A. skutchii, A. floridanum, A. saccharum, A. grandidentatum, and A. nigrum.

The understanding of the species traits of Acer L. growing in subtropical and tropical America is relevant because this region represents its most southern geographic range in the hemisphere. This study evaluates the morphological variation and updates the taxonomic status, distribution, and phylogenetic relationships of Acer in Middle America. A total of eight taxa are recognized. The presence of Acer negundo subsp. mexicanum is documented for Honduras, while five taxa are restricted to northern Mexico (Acer negundo var. arizonicum, A. negundo var. texanum, Acer glabrum var. neomexicanum, Acer grandidentatum, Acer grandidentatum var. sinuosum), whereas Acer binzayedii is endemic to western Mexico. Only Acer skutchii and A. negundo subsp. mexicanum are widely distributed in the investigated area. The populations are often fragmented and disjunct. The phylogenetic analysis identifies the A. grandidentatum populations from northwestern Mexico as a separate lineage. Descriptions, distribution maps, photographs, and conservation assessments of the species as well as a key to species are provided.

Se describe la estructura, composición, diversidad, relaciones ambientales y conservación de un bosque mesófilo con Acer saccharum subsp. skutchii (arce azucarero) recientemente encontrado en el municipio de Coahuayutla de José María Izazaga, Guerrero. Se registraron los individuos leñosos con ≥1 cm dap en parcelas circulares de 10 m de radio, y la altura de plántulas y plantas juveniles del arce azucarero en parcelas de 5.6 m de radio. Para cada especie se obtuvo su valor de importancia. Se utilizó la técnica de ordenación Escalar Multidimensional No-métrica (NMDS) para explorar sus correlaciones con variables edafológicas, coordenadas geográficas, de elevación y apertura de claros. Se registraron 43 especies de plantas leñosas en una superficie de 0.126 ha. Las familias mejor representadas fueron Asteraceae y Fagaceae. La distribución diamétrica de las plantas leñosas mostró una forma de “J” invertida, indicando regeneración exitosa. El arce azucarero fue codominante en el dosel con Carpinus caroliniana y Quercus uxoris. Tanto en la población de Guerrero, como en las otras cinco localidades donde habita el árbol en México y Guatemala, la mayoría de las correlaciones encontradas entre la presencia y ausencia de árboles, incluyendo Acer saccharum subsp. skutchii, y los factores ambientales se refirieron a las características de suelo. De las especies registradas en el estudio, 30% están incluidas en alguna categoría de riesgo. El régimen de incendios en la zona pone en peligro la persistencia de este árbol en el sitio de estudio.

Bray and Curtis ordination was used to explore which environmental variables explained importance values and the presence–absence of tropical tree seedlings, saplings and adults in La Escondida-La Cabana, Sierra de Manantlan, Jalisco, Mexico. The diameters of trees ≥2.5 cm DBH and the presence and height of seedlings and saplings were measured in nine 0.1 ha sites. Four matrices including presence–absence data and importance value indices for trees and seedlings and saplings were analyzed through Bray and Curtis ordination. The matrices were based on density, frequency, and dominance of adult trees as well as seedlings and saplings. The environmental matrix consisted of 18 variables, including elevation, slope, canopy gaps, disturbance, and soil variables. We recorded 63 tree species and 38 seedling and sapling species in the nine sites. The ordination explained 70.9% of the variation in importance value data for trees and 62.6% for seedlings and saplings. The variation explained in presence–absence data for trees was 67.1 and 77.4% for seedlings and saplings. The variance in the ordination axes of seedlings and sapling presence–absence data was poorly explained by the number of gaps in the tree, shrub, or herb layer, suggesting little light specialization by seedlings and saplings. Habitat specialization for soil nutrients appears to be important in explaining the presence–absence of seedlings and saplings. Seedling and sapling specialization along different soil microsites could promote species coexistence in this forest, while heterogeneity in light conditions may instead determine differences in growth and, thus, importance value of trees. We hypothesize that in tropical dry forest in Jalisco, Mexico, a habitat specialization for soil resources is likely more importance at early stages in tree life histories than in later life history.