Orchids constitute the largest family of monocots, with an estimated 20,000 species arranged in ca. 700 genera. Growing worldwide, most commonly in the tropics, they are renowned for the color and variety of their flowers and the intricacy of their pollinating mechanisms with insects and birds. Less well appreciated is the diversity of vegetative structures among orchids (roots, stems, and leaves), making possible their growth in a wide range of habitats, often quite specialized, including epiphytes upon other woody plants, subterranean forms, bulbs, vines, and shrubs. Dr. William Stern of the University of Florida is surveying the vegetative diversity of orchids to compile the first encyclopedic account of root, stem, and leaf anatomy of representatives of all 700 genera of the world's orchids. Working with colleagues in Florida and at the Kew Botanic Gardens in England, Dr. Stern will have access to living and preserved materials of all recognized orchid genera. Microscopic examination of slide preparations will allow standard comparisons across all the genera. In turn, comparative study will facilitate an evaluation of the range of environmental modifications found in orchid structures, and allow discrimination between homologous structures (those with a common genetic and developmental basis) from analogous structures (those that look similar in mature form but develop along different pathways). This first comprehensive survey of orchid vegetative anatomy will enhance further systematic, ecological, and morphological study of these fascinating plants.
