Systematics of subtribe Galinsoginae (Asteraceae)

点击翻译按钮获取中文摘要

9903800PaneroThe sunflower family Asteraceae is one of the largest families of flowering plants. They are ubiquitous in many areas of the world, especially those dominated by seasonally dry climatic conditions. The American continents have approximately half of the species of the family and most of the species of tribe Heliantheae. The tribe contains several economically important crops (sunflower oil) and many genera of horticultural value such as dahlias, marigolds, and zinnias. Taxonomic work on members of tribe Heliantheae has produced a wealth of information that has been recently synthesized by several authors in the form of major classifications for the tribe. These classifications disguise the fact that we still know very little about the ecology, evolution, and morphology of the major genera of the tribe and some of its subtribes. Subtribe Galinsoginae has approximately 125 species distributed mainly in Mexico, and further south to Ecuador in South America. There is little agreement on generic concepts in the group, with a consequent multiplicity of shifting species assignments; and the problem is compounded by the superficial similarity of some species to members of other tribes. Dr. Panero at the University of Texas is amassing molecular DNA evidence and morphological information for as many of the ca. 115 species of the subtribe as possible, in order to construct a phylogenetic framework for the group and to determine reliable morphological features for the lineages recognized as genera and subgenera. Field collecting in Mexico south to Ecuador will provide new materials for molecular, cytological, and morphological investigations, in association with foreign colleagues. The use of both nuclear and maternally inherited chloroplast genes in the analyses will help disentangle cases of suspected hybridization, which is also likely to relate to the known polyploids in the subtribe. A taxonomic monograph of the group, integrating molecular and morphological studies, is one goal, along with associated materials being posted to the website maintained at the U-Texas Herbarium.