FAYETTE, KIM* and LEO P. BRUEDERLE. Department of Biology, Campus Box 171, University of Colorado at Denver, P.O. Box 173364, Denver, CO 80217-3364. - Morphometric analyses support specific status for Eutrema penlandii Rollins (Brassicaceae).
Eutrema penlandii Rollins (Brassicaceae) was originally
described in 1950 from material collected in 1935 at Hoosier Pass in
Park County, Colorado. Penlandís alpine fen mustard is a globally rare
species restricted to continuously wet, alpine areas along a 25 mile
stretch of the Continental Divide in the Mosquito Range. The closest
relative to E. penlandii is the circumboreal E.
edwardsii R. Brown, with the two species being disjunct by over
2000 km. In 1987, W.A. Weber subsumed E. penlandii into its
North American congener, publishing the name E. edwardsii ssp.
penlandii (Rollins) W.A. Weber. Since then, there has been
considerable interest and debate among taxonomists and conservation
biologists regarding the systematic relationship between the two taxa.
Population genetic data revealed the two to be distinct (I = 0.914),
but provided little further insight into the level at which E.
penlandii should be recognized. In order to provide a clearer
understanding of the taxonomic relationship of these taxa,
morphometric data were collected for 34 continuous, quantitative
reproductive and vegetative characters from 136 herbarium accessions
of E. penlandii and E. edwardsii. Although the ranges
for all 34 characters overlapped, Mann-Whitney tests revealed
significant differences among the medians in 24 of the 34 characters,
while t-tests revealed significant differences among the means in 19
of 26 normally distributed characters. Multivariate analyses provided
further evidence with regard to the distinct nature of these taxa. The
first three principal components deriving from a principal components
analysis explained 61% of the variation in the data, with PCA
scatterplots revealing discrete groupings corresponding to species
boundaries. Similarly, discriminant functions analysis correctly
classified the taxa 100% of the time. These data reveal the two taxa
to be morphologically distinct and, coupled with the population
genetic data, further support recognition of E. penlandii at
the species level.
Key words: Brassicaceae, Eutrema penlandii