Wetland Plants and Plant Communities of Minnesota and Wisconsin
Appendix B
KEY TO THE WETLAND ASTERS (Aster) OF MINNESOTA AND WISCONSIN
(Modified from Gleason and Cronquist (1991) and Swink and Wilhelm (1994))
1A. Involucral bracts and peduncles glandular-pubescent; leaves auriculate-clasping;
herbage often glandular; rays very numerous, violet or amethyst to rosy, rarely
blue or white; large discs yellow to yellow-orange, distinctive ...............Aster
novae-angliae
1B. Plant with inflorescence pubescent or glabrous, but not glandular.
- 2A. Stem leaves with perfoliate or auriculate-clasping bases.
- 3A. Stems reddish, coarsely hispid; leaves not serrate, and not conspicuously
crowded; inner involucral bracts taper to a slender tip; rays violet;
nutlets glabrous; clonal ...............Aster puniceus
- 3B. Stems green or with purple lines or nodes, glabrous or sparingly
hispid; leaves not serrate but conspicuously crowded, particularly towards
the inflorescence; inner involucral bracts taper to a slender tip; rays
very pale blue or lavender; nutlets pubescent; clonal ...............Aster
lucidulus
- 3C. Stems zig-zag and are pubescent to glabrous toward the base; leaves
nearly perfoliate and coarsely serrate; rays blue to pale purple; nutlets
strigose; not clonal; rare ...............Aster prenanthoides
- 2B. Stem leaves usually not clasping at the base (not auriculate).
- 4A. Flowering heads are flat-topped (inflorescence is a corymb);
rays white; not clonal ...............Aster umbellatus
- 4B. Flowering heads not flat-topped.
- 5A. Stem leaves entire or serrate, more than 8 mm. wide, not
linear.
- 6A. Leaves pubescent beneath; rays white to slightly purple
...............Aster ontarionis
- 6B. Leaves glabrous or only pubescent along the veins.
- 7A. Leaves entire or subentire, 5 times as long as wide;
usually scabrous above; rays usually bluish-purple ...............Aster
praealtus
- 7B. Leaves mostly serrate, usually less than 5 times
as long as wide; usually not scabrous above.
- 8A. Flower heads secund (racemes 1-sided); leaves
usually villous or puberulent beneath, at least along
the midrib; rays usually white; not clonal ...............Aster
lateriflorus
- 8B. Flower heads form a panicle and are usually
not secund; inflorescence leafy; leaves are usually
glabrous beneath, except for occasionally ciliated
margins; rays usually white; clonal ...............Aster
simplex
- 5B. Leaves essentially entire, less than 8 mm. wide, linear.
- 9A. Leaves yellowish green, with revolute margins,
generally scabrous above; areolae isodiametric ...............Aster
praealtus
- 9B. Leaves green to dark green, margins not revolute,
glabrous or scabrous, areolae mostly rectangular.
- 10A. Ray flowers about 10 mm. long; flower heads
few, subcorymbose, terminal; plant slender; rays
white to pale lavender; typically found in open
cold bogs and open fens ...............Aster
junciformis
- 10B. Ray flowers less than 10 mm. long; flower
heads numerous, forms a panicle; plant stouter;
generally not found in cold bogs ...............Aster
simplex
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