THE MICHIGAN BOTANIST
For this investigation we collected specimens and directly examined living
plants from several sites across southern Michigan and analyzed herbarium specimens at the University of Michigan Herbarium (MICH). A total of 22 Aster
puniceus and 40 A. firmus plants were collected from co-occurring populations
at seven sites across southern Michigan: Waterloo State Recreation Area (Washtenaw County), Pinckney State Recreation Area (Washtenaw County), Hadley
Road (Washtenaw County), Furstenburg Park (Ann Arbor City Park, Washtenaw
County), Ives Road Fen (Nature Conservancy Preserve, Lenawee County), Lost
Nation State Game Area (Hillsdale County), and Bakertown Fen (Nature Conservancy Preserve, Berrien County). Plants were collected from September to
November in 1993, 1994 and 1995. Specimens were pressed, dried, and later examined. Five voucher specimens were deposited at MICH (Warners A. firmus
747, 757, 758; A. puniceus 756, 745, MICH). All remaining specimens are retained at the Calvin College Herbarium in Grand Rapids, Michigan.
From the collected specimens we quantified rhizome length, leaf midvein pubescence and capitulescence structure, and used these data to graphically illustrate differences. Specimens were collected with as much below-ground material
as possible so that various rhizome lengths could be assessed (see Figure 1).
Midvein pubescence was measured by averaging hair counts per millimeter of
midvein from three leaves per plant under a dissecting microscope. These measurements were taken from the abaxial surface of cauline leaves at an arbitrary
location within 3 cm from the base of the leaf. To quantify differences in capitulescence architecture we created a variable, mean BRC (Branching Ratio in the
Capitulescence). Mean BRC is the mean ratio of non-flowering to flowering segments (cm) on the three lowermost capitulescence branches (Figure 2).
We also gathered data from living plants in coexisting populations at Warren
Townsend Park (Kent County), Pickerel Lake Nature Preserve (Kent County),
Flat River State Game Area (Montcalm County), Waterloo State Recreation
Area (Washtenaw County), Ives Road Fen (Lenawee County), and Bakertown
Fen (Berrien County). Observations were made between 3 July and 30 August
1998. At these sites we collected data for three variables (stem thickness, number of shoots per plant and stem pubescence) from a total of 22 Aster puniceus
and 28 A. firmus plants. Stem thickness was measured at a point 20 cm above the
soil surface. The number of living shoots (current year) from the base of a plant
was counted after sufficient surface soil was removed to confidently assess
which shoots emerged from the same below-ground structure. Stem pubescence
was measured by counting the number of hairs (per 25 mm2) on the stem at a
point 60 cm above the soil surface.
To assess data from a broader geographical region than southern Michigan,
148 specimens of Aster puniceus and 68 specimens of A. firmus were examined
at MICH by qualitatively evaluating four characters: pubescence in the capitulescence, stem pubescence, pubescence on abaxial surface of leaf midveins,
and underground parts. A complete list of citations for each of these specimens
may be requested from the authors.