/ Evidence for a Species-Level Distinction of Two Co-occurring Asters: Aster Puniceus L. And Aster Firmus Nees
ï~~1999 THE MICHIGAN BOTANIST 25 1999 THE MICHIGAN BOTANIST 25 E E W L CU i C CU > CV 6 CU CU J 0 0 0 0 O 0 o 000 O A. puniceus * A. firmus 0 1 2 3 4 5 Mean BRC U C) a FIGURE 4. Evaluation of belowground structure, mean BRC, and leaf midvein pubescence from collected specimens. (a) Mean branching ratio in the capitulescence plotted against mean number of hairs on abaxial cauline leaf midvein. (b) Maximum rhizome length to next year's shoot plotted against mean branching ratio in the capitulescence (see Methods). 40 0 10 20 30 40 50 Maximum length to next year's shoot (cm) 60 70 DISCUSSION In our evaluation of these plants we have followed two stated lines of advice offered for those who conduct taxonomic research within Aster. First, Gleason & Cronquist (1991) and others (Jones 1980b; Semple & Brouillet 1980a; Voss 1996) stress the importance of considering the entire plant body when generating keys or making identifications within this genus. Shinners (1941) has also raised this concern, emphasizing that "rootstocks are of critical importance." Second, since many of the species within Aster are so variable, it has been recommended to use a suite of characters to delineate species, rather than a single or limited number of traits (Carlquist 1976; Cronquist 1943; Semple & Brouillet 1980a). Several of the traits we used (stem pubescence, capitulescence architecture, leaf midvein hairs) have been used qualitatively by other authors to suggest character overlap (Jones 1989, Voss 1996). However, by carefully quantifying these
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