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
