Discipline: Biological Sciences
Ieasha T. Henderson - Harris-Stowe State University
Co-Author(s): John MacDougal , Harris-Stowe State University and Missouri Botanical Garden, MO
Passionflower vines (Passiflora, Passifloraceae) have the widest variety of leaf shapes of all plants in the world (Ulmer & MacDougal, 2004). Most monographic studies in the genus have included leaf shape to distinguish different species, but these have always been described in words, e.g. transversely elliptic, the lobes spreading widely, the center lobe reduced (Krosnick et al., 2013). The very few studies of leaf shape in this genus were not used taxonomically to distinguish closely related species, and because they were mathematically highly technical (Minkowski fractals, Plotze et al. 2005), they are of little use in the field to ecologists.
The research question is whether leaf shape as visualized by a few simple measurements and ratios can be used to describe closely related species. The model system is five species of passionflowers with similar leaves of the subgenus Decaloba, supersection Hahniopathanthus, a monophyletic group occurring in Central America and southern Mexico. Specimens from the Missouri Botanical Garden as well as scans of specimens from other herbaria were measured manually or digitally, ratios computed, and the results plotted on 3-axis graphs.
Results show that some of the species can indeed be distinguished using a few simple leaf ratios. This analysis shows promise for future monographic and field-based taxonomic keys, although variations due to leaf position on the plant must be considered.
Funder Acknowledgement(s): NSF HBCU-UP Implementation Grant to HSSU.
Faculty Advisor: John MacDougal, macdougJ@hssu.edu
Role: Measurement of all specimens, databasing, computations, graphing values, comparing species, conclusions from the analysis, preparation of presentation.