Aster family (Asteraceae)
This herbaceous perennial plant becomes 3-7' tall, forming either a
solitary or a cluster of central stems that branch occasionally to
central stems are light green, vertically veined, glabrous, and
sometimes glaucous; they are terete (circular in circumference), except
for the decurrent bases of the leaves. This latter characteristic
causes them to appear heavily winged. Spreading to drooping alternate
along the entire length of these stems at regular intervals, becoming
gradually smaller in size as they ascend. The leaves of the
central stems are up to 7" long and 1½" across; they are
oblong-lanceolate in shape, while their margins are entire (toothless)
and often slightly wavy (vertically) or undulate (horizontally). These
leaves taper gradually, forming narrow acute tips, while their bases
strongly clasp the central stems. The basal margins of these leaves
extend downward 1-3" along their stems, forming pairs of wings up to ¾"
across. The upper leaf surface is medium to dark green and glabrous,
while the lower leaf surface is a slightly lighter shade of green,
glabrous, and sometimes glaucous. Leaf venation is pinnate; the central
veins of these leaves are prominent, particularly toward their bases.
Slender ascending lateral stems develop from the axils of the leaves,
particularly along the middle to upper leaves of the central stems. The
alternate leaves of these lateral stems are up to 3" long and ½"
across; they are elliptic or linear-lanceolate in shape, entire along
their margins, and either sessile or decurrent at their bases. When
their bases are decurrent, the basal margins of these secondary leaves
extend downward up to 1" along their stems, forming pairs of wings up
to ¼" across.
The central stems terminate in large panicles of
flowerheads (up to 2' long and 2' across) that are more or less
dome-shaped. On robust plants, many lateral stems will also terminate
in smaller panicles of flowerheads. The branches of these
inflorescences are similar to the stems, except they are less winged
from the decurrent bases of their leafy bracts. These bracts are up 3"
long and ½" across and they are similar in appearance to the leaves of
lateral stems, although they can become smaller in size. Each
daisy-like flowerhead is ¾–1" across, consisting of 40-60 ray florets
that surround a dense head of 180+ disk florets. The ray florets are
pistillate (female), while the disk florets are perfect (male and
female). The petaloid rays of these flowerheads are linear-oblong in
shape and white (rarely lavender or light purple). The corollas of the
disk florets are about 2 mm. long, yellow, tubular in shape,
and 5-lobed along
their upper rims. Around the base of each flowerhead, light green
phyllaries (floral scales) are arranged in about 3 overlapping series.
These phyllaries are linear-oblanceolate in shape, membranous along
their margins, and appressed together. When the flowerhead blooms,
these phyllaries form an involucre that is shaped like a shallow plate
or flat disk.
The peduncles (basal stalks) of these flowerheads are up to 3" long.
The blooming period occurs during late summer into autumn, lasting
about 1-2 months. Afterwards, the fertile florets
are replaced by achenes about 1.5–2.5 mm. in length. These achenes
are obovoid, somewhat flattened, and slightly winged along their
margins; solitary pairs of awn-like scales occur at their apices. The
can be blown about by the wind or float on water. The root system is
shallow and fibrous.
The preference is full sun,
wet to moist conditions, and fertile soil containing loam, clay-loam,
or silty deposits. However, this plant can adapt to drier conditions in
gardens if it is watered during dry spells. Growth and development from
seed is usually rapid, as this plant can bloom during the first year.
Some stakes or a wire cage may be necessary to keep it upright in a
flower garden or rain garden.
Range & Habitat:
False Aster is largely restricted to several counties in central and SW
Illinois, where it is found along the floodplain of the Illinois River
This species has also been found at Lake County
in NE Illinois, where it is adventive.
Outside of Illinois, a few small colonies of plants have been found
along the floodplain of the Mississippi River in eastern Missouri.
Decurrent False Aster is a rare plant that is listed as 'threatened' in
Illinois, and it is also listed as 'threatened' at the Federal level of
the United States. Populations of this plant can vary considerably from
year-to-year depending on the pattern of precipitation and flooding
along the Illinois River and Mississippi River. Flood-control projects,
wetland habitat destruction, and excessive sediment in the water during
floods can undermine the long-term survival of this plant. Habitats
include riverbottom prairies, shallow marshes, and mud flats along
major rivers. This is a conservative species that is found in wetland
habitats along rivers that are prone to occasional flooding. Such
floods reduce competition from other herbaceous plants and woody
Very little is known about the
floral-faunal relationships of Decurrent False Aster (Boltonia
decurrens), although it is probably similar to the more
Aster (Boltonia asteroides). Pollinators of the
consist of long-tongued bees, short-tongued bees, wasps, flies,
butterflies, skippers, and beetles. Both nectar and pollen are
available as floral rewards. One bee species, Perdita
boltoniae, is a
specialist pollinator (oligolege) of Boltonia spp.,
and another bee,
Melissodes boltoniae, may be a weak oligolege of
(Robertson, 1929). The larvae of a beetle, Microrhopala xerene,
the leaves of False Aster and other species in the Aster family (Clark
et al, 2004). The relationship of Decurrent False Aster to vertebrate
animals is probably similar to many wetland asters (Aster spp.).
A flower garden in Champaign, Illinois.
This rare wildflower adapts to gardens readily and it should be
cultivated more often. Decurrent False Aster (Boltonia
decurrens) is similar in appearance to False Aster (Boltonia
except the latter species lacks decurrent wings along its stems.
Decurrent False Aster also lacks the wandering rhizomes of the latter
species, although it is capable of developing more than one shoot from
its root system. Decurrent False Aster is sometimes classified as a
variety of this latter species, or Boltonia asteroides
decurrens. False asters (Boltonia spp.)
differ from asters (Aster spp., Symphyotrichum
etc.) by lacking tufts of hair on the apices of their achenes.
Instead, the achenes of false asters have awn-like scales in pairs. In
addition, the bases of their flowerheads (involucres) are more
flattened in appearance (shaped like a shallow dish or flat disk),
those of asters are more cup-like or turban-shaped (turbinate). The
False Asters resemble those of fleabanes (Erigeron spp.),
except the flowerheads of the latter bloom earlier in the year and
their achenes have sessile tufts of bristly hairs.