I should have written a little more about Obolaria in yesterday’s post, which I realized when someone asked a question in the comments.
The thing is, very little is known about this plant. I was able to find one paper* on the subject; in the introduction, the authors state:
Although morphological descriptions of O.virginica exist in various floras (e.g., Radford et al. 1968, Fernald 1970, Wood and Weaver1982, Gleason and Cronquist 1991), information about reproductive capacity or ecological parameters that might influence growth and development is lacking. For example, no information exists about the pollination biology of pennywort, nor have there been any studies to examine basic soil parameters to determine optimal growing conditions of this species.
The paper is interesting, but has no further discussion of pollinators.
I’m not patient enough to sit and watch a stand of Obolaria to see what, if any, insects come to visit. It would be an interesting project, though.
*Notes on the Biology of Obolaria virginica (Gentianaceae) in Southeast Missouri, and the Effects of Leaf Litter on Emergence and Flower Production
Diane L. Wood and Allan J. Bornstein
Department of Biology, Southeast Missouri State University
One University Plaza, Cape Girardeau, Missouri 63701
Do you see any flowers in this photo? They are there, slightly below and to the right of center. You’ll probably have to click on the photo to really see them.
This is pennywort, Obolaria virginica, a species in the Gentianaceae. It grows on the forest floor in deep leaf litter, from Pennsylvania and Ohio south and west as far as eastern Texas. Pennywort has little chlorophyll, so it doesn’t photosynthesize much if at all; instead, it derives energy from a complex relationship with a fungus and a host plant. This relationship is called myco-heterotrophy.
You may find some older sources that describe pennywort as saprophytic, but that concept is obsolete. As I was researching and fact-checking, I came across a great explanation from the USDA Forest Service: What Are Mycotrophic Wildflowers?
The flower color ranges from the medium purple shown here to nearly white, and the thick leaves are more purple than green. Th entire plant stands only a few inches tall.
Thanks to Katie for showing me where to find a good stand of these plants.
You know how birders keep “life lists” of their sightings? I have a life list of wildflower finds. I was delighted to add three new plants to it earlier this week, after visiting Rachel Carson Conservation Park: pinxter azalea, pennywort, and an orchid.
…and that’s about the most interesting thing I can say about pennywort. It’s a low-growing forb of moist woodlands, ranging from Texas northeast into Pennsylvania. There are no conservation issues. Obolaria is a monotypic genus (meaning there are no other species of Obolaria). I saw no other pennywort plants in the area.
“Pennywort”, by the way, is a popular name; there are quite a few plants (entirely unrelated to each other) that are called “pennywort”.
That’s all, folks. Tomorrow: the orchid. You can see a bud peeking up behind the pennywort in the photo above.