9629767 Philbrick Among some of the poorest known groups of tropical plants are the "riverweeds" of the New and Old World, some 19 or so genera of the family Podostemaceae. Many of these flowering plants grow attached to rocks in swift-flowing streams and rapids in tropical regions, and can be locally abundant. They harbor invertebrates, larval fish, amphibians, algae, and aquatic mosses, and are likely important in tropical river ecosystem function. With their stereotyped, ribbon-leaf morphology and infrequent flowering and fruiting, they provide few characters upon which to construct a reliable classification. Problems with species identification thus hinder ecological research; analysis of biogeography and migration pathways is hampered by lack of knowledge of phylogeny. Dr. C. Thomas Philbrick of Western Connecticut State University with colleague Dr. Donald Les of the University of Connecticut will be collecting and studying riverweeds in Mexico and South America, with additional work in India on Old World taxa. The goal is to collect new material for critical taxonomic study of vegetative and reproductive features, and to supplement these with new molecular information from DNA sequencing. Another component of the project is a series of common-aquarium growth experiments, to factor environmental and genetic effects on morphology. The inventory and documentation of tropical biodiversity remain priorities among taxonomists and evolutionists. The peculiar riverweeds of the angiosperm family Podostemaceae are the focus of modern monographic and phylogenetic research by Dr. Philbrick and Dr. Les, in collaboration with foreign colleagues in Mexico, South America, and India. An improved classification of these plants, with reliable means of species identification and a robust estimate of phylogenetic relationships, will advance understanding of their ecological roles and evolutionary histories.
