Passiflora represents a diverse group of more than 560 species of vines and trees primarily found in Central and South America. These plants are best known as the source of tropical passionfruit, but are also widely cultivated for their beautiful, complex flowers. Passionflowers appear to be a recently-evolved lineage that has experienced rapid species diversification. Many species are poorly understood with regard to morphology, geographical distribution, and conservation status, especially in the largest lineage of passionflowers, subgenus Decaloba, with 235+ species. This study will synthesize modern and traditional approaches to address these problems, using DNA sequence data, scanning electron microscopy, and observation of fresh and preserved specimens. Field work will enable collection of fresh material and documentation of species distributions. This project will yield a revision of all species in Decaloba, and will provide a modern evolutionary framework within which to address questions about the evolution of floral shape, pollination syndromes, floral development, and the biogeographical history of the lineage.
This study will address important biological and evolutionary questions in an especially charismatic group of plants. Undergraduate and graduate students will participate in the research. Undergraduates at Keene State College and Harris-Stowe State University, institutions that primarily enroll underrepresented groups in the sciences, will especially benefit from involvement in this study. Summer workshops at Rancho Santa Ana Botanic Garden will involve students from the local community. Field expeditions will build international collaborations among U.S. scientists and colleagues in Mexico, Central America, and South America. All results of this project will be available through a website hosted by the Missouri Botanical Garden.
The Passion flowers or the genus Passiflora was described in 1753 by Linneaus and we are still in the process of learning about this fascination group of about 585 species. The genus has been subdivided several times; the last attempt established five major groups; two very large groups or subgenera Passiflora (250 species) and Decaloba (250 species) and three smaller subgenera Astrophea (58 species), Deidamioides (14 species), and Tetrapathaea (3 species). Almost all Passion flowers are found in the new world from the USA to Argentina with a few exceptions. The subgenus Tetrapathaea is from Australia, New Zeeland, and Papua New Guinea and a group of about ~20 species from the subgenus Decaloba is also found in the old world both in Australia, southeast Asia, China, and India. Our study aim at elucidating the evolutionary history of subgenus Decaloba, gain knowledge of the important characters that describe and characterize the different evolutionary lineages, provide an updated monograph to the species of Decaloba, as well as information that would help to conserve the species in the wild. The evolutionary history of the group will be presented next year by other members of the project. Preliminary results indicate that Tetrapathaea is sister to Decaloba, the other dispersal event from the new world to the old took place later, and the sister or closest living relative to this group is a species from the Caribbean. All formally recognized and named groups inside the subgenus Decaloba remain, but some rearrangement of species is needed in a few groups, which indicate that some characters used traditionally are of less importance while other previously thought to be unimportant in reality are informative. Our monographic work is based on approximately 18,000 collections (not including duplicates). We have established a database to capture information from the collections housed in approximately 150 museums worldwide. For each specimen we can store 500 variables or observations pertaining to the individual collection. When a decision is made as far as what specimens belong to which species, the descriptions can be prepared and stored in our database. Botanists have done this type of work for more than 250 years, most of this time individual observations were not recorded of a specific specimen, but summarized and synthesized to make it into a description of the species, which is best understood as the construct or hypothesis of the scientist doing the work. This tradition makes for a very inefficient long term system, where all information from previous attempts to understand the species are discarded every time a new monograph is warranted, and equally important the hypotheses presented cannot be tested. Each attempt to monograph a group has to deal with a larger and ever increasing amount of information and if we start from zero every time, we have created a Sisyphus work for ourselves that will continue to provide numerous untestable hypotheses (species). Our approach breaks with this system and will make our observations and measurements available for the following generations to use, so that our decisions and hypothesis can be tested over time. We are still measuring specimens and synthesizing information and during this process we have discovered 30 new species. Our understanding of the evolutionary history of the group, knowledge of the morphology as well as where they grow will be used to council conservation decision to be able to conserve and preserve these most interesting species, which still are harboring many mysteries in biology and ecology.
