CONSAUL, LAURIE L.* and LYNN J. GILLESPIE. Research Division, Canadian Museum of Nature, Box 3443, Station D, Ottawa, ON, Canada K1P 6P4. - Preliminary morphological and molecular analyses on alkali grasses (Puccinellia, Poaceae) in the Canadian arctic archipelago.
Alkali grasses (Puccinellia, Poaceae) have traditionally posed
problems for identification, and the species in the Canadian arctic
archipelago (CAA) are no exception. Although there is considerable
morphological variation within the genus, circumscription of taxa is
problematical because of overlap of character states and many
apparently intermediate specimens. While two species are quite
distinct, nine other traditionally recognized species of the CAA have
poorly defined species boundaries. The aim of this study was to define
the taxonomic limits of species or species groups based on
morphological data. In the first part of the investigation, we
redefined the character states of several floret and spikelet
characters that had been difficult to interpret in previous keys and
descriptions. The second part of the study involved analyses on a
morphological character set that included these revised characters
plus other characters previously shown to have low plasticity in this
genus. These analyses showed that P. vahliana was distinct
based in part on glume lengths, P. phryganodes was a distinct
stoloniferous species, and P. langeana was readily
distinguished by its small size and lack of hairs. The remaining
species were less clearly distinguished in the ordination analyses
performed. The P. arctica aggregate separated from the other
taxa, but there was no resolution of species within this group.
Hypotheses of species boundaries in the arctic taxa, based on current
evidence, are presented. Our present aim is to test these hypotheses
with more detailed morphological, anatomical, and molecular analyses.
Initial screening of the above taxa for 16 enzymes revealed very low
levels of allozyme variation within the genus, with potential markers
for P. langeana and P. vahliana in one enzyme system.
Restriction site analysis of PCR amplified DNA of eight species showed
only minor variation for P. vahliana and P. phryganodes,
and none for six other species analyzed.
Key words: Canadian arctic, morphology, ordination analyses, Puccinellia, species boundaries