Overview
A perennial plant in the sunflower family with a bright yellow corolla, Virginia sneezeweed was once thought to be endemic to its namesake state, until it was found in Missouri by a scientist investigating a botanical mystery.
In 1989, professor John Knox of Washington and Lee University drove to Missouri to collect samples of a plant a respected botanist had been unable to identify along a roadside there 30 years earlier. Knox, who had studied Virginia sneezeweed in Virginia for years, had reason to believe the unidentified plant was also Virginia sneezeweed.
He later confirmed his hypothesis through a multi-year experiment in which he grew the plant from seeds he gathered in Missouri and transplanted to Virginia sneezeweeds’ unique habitat: ephemeral wetlands that undergo irregular periods of flooding and drought.
In 2001, Knox’s finding was reaffirmed through genetic analysis, inspiring a pilot propagation effort and extensive surveys for additional populations in Missouri — an effort involving partners from the Missouri Department of Conservation, the Missouri Botanical Garden, the Center for Plant Conservation, and the U.S. Fish and Wildlife Service.
Today Virginia sneezeweed is thriving in both Missouri and Virginia.
Scientific Name
Identification Numbers
Characteristics
Habitat
Virginia sneezeweed prefers seasonally flooded sinkhole ponds – a globally rare habitat. However, it has also been found in disturbed sites in Virginia that appear as seasonally wet meadows, depressions in lawns, roadside ditches, and the margins of farm ponds.
In Missouri, its habitat ranges from the margins of less-disturbed sinkhole ponds and wet meadows, to temporary wetlands in hayfields, roadside ditches, cattle ranches, and rural airports.
These habitats act as temporary wetlands, and some are dependent on groundwater inputs, while others rely on precipitation for recharge. Sinkholes meet the species' needs naturally, with the perfect hydroperiod, soil chemistry, pond basin morphology, and water depth, but these conditions can be mimicked by human activities.
The species occurs more often at high elevations, a possible link to geology (limestone or dolomite) associated with low soil pH. The species only occurs in acidic soils in Virginia.
Within the Ozark Highlands section of Missouri, the central subsection area was most likely to support the species due to a higher proportion of open lands supporting karst features.
Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.
Physical Characteristics
Virginia sneezeweed can reach a height of 3.5 feet.
This herbaceous plant has yellow flowers.
Life Cycle
Virginia sneezeweed employs a breeding system of self-incompatibility, meaning plants can mate successfully only with individuals that are genetically compatible.
The species has a tendency to experience short-term local extirpation of plants due to its specialized adaptive tolerances for stress associated with high fluctuations in water levels and specific soil chemistry.
Water depth and duration of standing water in Virginia sneezeweed habitats varying greatly year-to-year, population sizes and stage class abundances also vary greatly from year-to-year. Some years, following long continuous inundations accompanied by abundant living and dead flotsam, a population may crash from tens of thousands to zero or near zero individuals. Additionally, drought conditions could contribute to the species not being detected during certain years.
With the high yearly variability of adult populations at a given location, researchers found that seed survival within the seed bank was the best indicator of the persistence and viability of Virginia sneezeweed populations.
Timeline
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