Imported from first blog: Peregrination Notebook.
I came across an interesting journal article. Southeastern Naturalist published a study by Rhonda L. Rimer and James W. (Bill) Summer called “Range and Ecology of Helenium virginicum in the Missouri Ozarks“. It seemed like it wouldn’t have heavy statistics, so I gave it a shot.
Helenium virginicum, also known as the Virginia Sneezeweed is a rare herb of about 70-110 cm originally thought to exist only in the Shenandoah Valley of Virginia. For reasons not addressed in the article, the plant established a small cluster of populations in the Missouri Ozarks (south-central of the state). Nowhere else in between–just Virginia and Missouri so far.
What I wasn’t expecting when I started reading was that H. virginicum grows on top of karst landscapes, specifically on the rims of sinkholes and frequent-flood zones next to ponds. Howell County, Missouri is apparently ideal for them. Most of the county is on a plateau which is the topography associated with sinkholes. In this higher elevation area of the Ozark Mountains is roubidoux sandstone, which disintegrates into the favored acidic soil. Acidic soil and open access to sunlight are the two minimum requirements for this plant. Other than open areas next to sinkholes, they grow in some roadside ditches and grassland on top of more or less bowl-shaped bedrock. The ditches and concave bedrock create an environment that traps rain and seasonally floods, just like the favored ponds and karst pits.
This study found that the Missouri populations were greater in number than the Virginia populations and overall had the same ecology. The Virginia Sneezeweed also tolerates both pristine wilderness and disturbed environments, so considering that there are other karst landscapes between Missouri and Virginia, it’s a wonder that they haven’t been found elsewhere. I don’t know much about the varieties of sandstone, but the other factors associated with these plants aren’t exactly rare. My guess is that someone from Shenandoah Valley went to Howell County with a few flowers and the numbers grew from there.