48 NEBRASKAland • NOVEMBER 2017
bottoms of Colfax and western Dodge
counties, including the Fertig prairie,
and never before encountered purple-
headed sneezeweed. This makes me
believe that, indeed, the Fertig plants
represent our state's only population,
which in turn, begs the question, how
did they get there?
Similarly, other plant species
that range over the eastern United
States have unexplainable, isolated
populations along eastern Nebraska
streams. Our state's only colony of the
delicate, white-flowered snow trillium,
for example, grows in oak woods on
limestone bluffs above Weeping Water
Creek in Cass County, 200 miles
from its nearest known population in
northwestern Missouri.
Perhaps purple-headed sneezeweed
has existed in eastern Nebraska for
millennia and the Fertig plants are
relicts of an ancient, once widespread
population in the region. For several
thousand years after the close of the
last Ice Age, which ended roughly
12,000 years ago, the Great Plains'
climate was wetter than at present.
Plausibly, during this mesic period,
purple-headed sneezeweed migrated
up the Missouri River valley from the
southeast into eastern Nebraska. When
the climate began to dry starting about
8,000 years ago, the sneezeweed's
range would have contracted eastward,
leaving only scattered populations
in our moist, eastern stream valleys.
Since Euroamerican settlement in the
mid-1800s, nearly all the region's
bottomland meadows have been plowed
or severely degraded by overgrazing
and invasive plants, leaving the Fertig
sneezeweeds as sole survivors.
Another possibility: purple-headed
sneezeweed established more recently in
the Fertig Prairie via long-distance seed
dispersal. Historically, large ungulates
Common sneezeweed flowers greet the early morning sun in a wet meadow near
Worms, Nebraska, in Merrick County. The flower heads of sneezeweeds, as well as
other members of the aster family, are composed of numerous small flowers that
collectively mimic typical flowers and act to attract pollinators. Showy, single-petaled
"ray flowers" line the flower heads' outer edge, while hundreds of yellow, petal-less
"disk flowers" occupy their center.
The "winged stem" of common
sneezeweed. The wings are often more
prominent on lower stems.
WINGED
STEM
