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THE MICHIGAN BOTANIST
Vol. 38
60 0O A. puniceus
0 A. firmus
"
E
50
40 0 0
4) 4).2 c; 30
u0
K 20 *
01 " "
S 10 FIGURE 3. A comparison of belowground structures of the
o two asters: length to pre0 0 20 vious year's shoot plotted
0 1,0 " 20 30 40 50
against the mean length
Length to previous year's shoot (cm) to next year's shoot.
to have variable numbers of cauline leaf midvein hairs (> = 6.8/mm, sd = 2.3),
while A. firmus midveins were typically glabrous (> = 0.14/mm, sd = 0.37). The
two anomalous individuals (one A. puniceus without hairs and one A. firmus
with hairs) maintained other characters consistent with their taxon. Mean BRC
was consistently lower in A. puniceus (x = 0.86, sd = 0.39) than in A. firmus (x
= 3.38, sd = 1.43), indicating that the heads of A. firmus are much more crowded
along the outermost part of the capitulescence.
Observations of living plants in the field yielded additional quantitative data
that further delineate the two asters. Figure 5 illustrates these differences using
the variables stem thickness (at 20 cm above the soil surface), number of shoots
from the base of a plant, and number of stem hairs (per 25 mm2 on the stem 60
cm above soil surface). Aster puniceus can grow in clumps of several shoots per
plant (> = 2.4, sd = 1.6), whereas we always found A. firmus shoots arising
singly (x = 1.0, sd = 0). Aster puniceus also commonly displays thicker stems (x
= 7.2 mm, sd = 1.5) than A. firmus (x = 4.0, sd = 0.93) and the stems of A.
puniceus are more densely pubescent (x = 15.7, sd = 4.5) than are the stems of
A. firmus (x = 2.3, sd = 1.9).
The qualitative data gathered from specimens at MICH illustrate general
trends in pubescence differences and further supported differences we had quantified from below-ground material. Four comparisons in pubescence patterns
were made (Table 1). Stem and leaf pubescence occurred more commonly and at
greater density in Aster puniceus. However, pubescence in the capitulescence
was found in distinct lines more frequently in A. firmus.
We also attempted to compare below-ground material from the MICH specimens (Figure 6). Unfortunately, the majority of herbarium specimens (over 60%)
did not include sufficient below-ground material to make such a comparison.
However, of those with sufficient root material, the vast majority of Aster
puniceus specimens exhibited a caudex, and nearly all A. firmus specimens had
extended rhizomes.
