RANKER, TOM A.*, KENDRA A. MINGO, CHRISSEN E. C. GEMMILL, AND WINONA CHAR. University Museum & EPO Biology, University of Colorado, Boulder, CO, 80309; SMILE Program, Oregon State University, Corvallis, Oregon 97331-3510; Centre for Biodiversity and Ecology Research, Dept. of Biological Sciences, University of Waikato, Hamilton, New Zealand 2001; Honolulu, HI. - Systematics and classification of Hawaiian Sesbania (Fabaceae).
Populations of Sesbania in Hawaii exhibit a classic situation
found among many Hawaiian plant taxa in that there is much
morphological variation across populations but the variation for any
single trait appears as a cline. Such apparent clinal variation has
lead to conflicting classifications in Sesbania with from one
to seven species being recognized by various workers. We have
employed data from isozymes, DNA sequence variation (SSCP of
ITS-nrDNA), and morphology in multivariate analyses and phylogenetic
analyses to address the following questions: 1) Are populations of
Hawaiian Sesbania a monophyletic group? 2) Can the different
populations be discriminated from each other multivariately? 3) Do
individual populations or groups of populations represent discrete,
multiple evolutionary lineages? 4) What are the phylogeographic
relationships of populations/taxa? 5) What are the implications of
our results for the classification of Hawaiian Sesbania?
Preliminary results suggest the following: Hawaiian populations of
Sesbania are a monophyletic group; some single populations and
some groups of populations are distinct and non-overlapping for
various combinations of data and they may represent discrete lineages;
the data support the recognition of at least the following taxa, here
listed as informal names based on the work of Char:
"tomentosa-Hawaii". Even when all populations of Hawaiian
Sesbania are treated as a single species, this is a rare taxon.
The classification proposed here suggests that Hawaiian
Sesbania is a complex of extremely rare and endangered species.
Key words: Fabaceae, Hawaii, Sesbania