SAARELA, JEFFERY M.1*, PAUL M. PETERSON2, ROBERT J. SORENG2, and RALPH E. CHAPMAN3. 1Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, CANADA; 2Section of Botany, Department of Systematic Biology, National Museum of Natural History, Smithsonian Institution, Washington DC 20560, USA; 3Applied Morphometrics Laboratory, National Museum of Natural History, Smithsonian Institution, Washington DC 20560, USA. - Taxonomy of Brachyelytrum (Poaceae) based on morphology and phytogeography.
Brachyelytrum is a small and morphologically distinct genus of
grasses distributed throughout eastern North America and eastern Asia.
In the past, plants in the genus have been variously treated as one to
three taxa at the specific, subspecific, and varietal ranks. The
taxonomy of Brachyelytrum has not been investigated across its
entire geographic range. Based on herbarium and field studies, we
present a revised taxonomic treatment. Morphological and label data
were studied on approximately 665 herbarium sheets. A multivariate
statistical analysis of 19 morphological characters, measured on 110
specimens representing both the morphological and geographical range
of variation in Brachyelytrum, was conducted to investigate
patterns of morphological variation and species limits. Scanning
electron microscopy was used to search for taxonomically informative
micromorphological characters. Geographic data were obtained from
specimens and the literature and were plotted to determine the
geographic distributions of characters and taxa. Based on a
combination of morphological and phytogeographical data, we recognize
three distinct species in Brachyelytrum. Brachyelytrum
erectum and B. aristosum are distinguished by differences
in lemma hair length and lemma width and have somewhat overlapping but
ecologically distinct distributions in eastern North America, while
B. japonicum is distinguished by its narrow leaf blades and
long rachillas and is distributed in eastern Asia. Molecular studies
are currently underway to further characterize these species.
Key words: Brachyelytrum, multivariate analysis, Poaceae, taxonomy