A Rare Plant Census Experience

by Mark Elliott, President, Paynes Prairie Chapter

Conradina etonia in Etoniah Creek SF. Photo
by Mark Whitten.
On Tuesday October 30th, 2018 Charlie Pedersen, a Biologist with the Florida Forest Service (and Paynes Prairie Chapter member) led a group of intrepid botanists/biologists from multiple organizations including Santa Fe Audubon, Bok Tower Sanctuary and 2 additional members of Paynes Prairie chapter through the undergrowth of Etoniah Creek State Forest to count Etonia rosemary (Conradina etonia) plants. Etonia rosemary, endemic to Etoniah Creek white sand scrub1, wasn’t described until 1991. In the abstract of the paper2 first describing it, the authors (Kral and McCartney) stated that “C. etonia is a narrow endemic, that is on land that is presently being developed for residential use and that it therefore should receive high conservation priority.”

It is now on both State and Federal lists of endangered plants. Based on reports from Charlie Pedersen, these plants have been counted annually for about 18 years. In 2000, biologists counted about 700 individual plants. A few years later 2369 plants were counted; in 2018, we counted less than 1500. Most individuals now occur on state forest lands, but some also grow on private inholdings within the forest.

Are you interested in improving habitat for this endangered plant? Join us on our workday in Etoniah Creek SF, March 16-17th, 2019.

Volunteers pose in front of a patch of flagged plants.
Photo: Mark Whitten

We split into 2 groups and the smart group got to count the plants along the roadside. The other group, of which I was a member, was obliged to bushwhack our way through the overgrown scrub from plot to plot. The botanists flagged the plants, one volunteer counted the flags and another recorded the numbers. One interesting observation made by the ecologically observant botanists/biologists was that seedlings were only observed in recently opened or disturbed sandy areas such as those exposed by the roots of a fallen tree or by mechanical disturbance.  Mature plants struggled in the dense shade; those in full sun or light shade seemed to be the most healthy. Only a few flowers and pollinators were observed in dense shade. At the end of the survey, our discussion ranged from the current conditions to what might be needed to optimize growing conditions and even what might have optimized the growth of Etonia rosemary during the ice ages when scrub habitats were more widespread.

A flagged C. etoniah seedling in a recently
disturbed area. Photo: Mark Whitten
Unlike some scrub and sandhill plants, Etonia rosemary does not tolerate frequent fires; it seems more adapted to mechanical disturbance to open up suitable habitat. Some biologists have suggested that such plants might have depended upon soil disturbance of extinct megafauna (such as mastodons, mammoths, gomphotheres, and giant sloths). I went home and looked up Gomphotheres. Apparently Florida may have been one of their last strongholds before extinction.

Ironically present-day management of Etonia rosemary might require disturbance by heavy machinery (plus occasional fire) to mimic the effects of these extinct mammals. Much more research is needed.

A very photogenic C. etonia flower. Photo: Mark Whitten.

Back to the survey: We counted a total of 1475 plants. Population estimates fluctuate from year to year, but have never exceeded 2400 plants. There is an effort by the Putnam Land Conservancy to continue to buy some of the private lands where it grows3. And, The USFWS is currently conducting a Species Status Assessment (SSA) to review the literature, research, monitoring, and land management needs of Etonia rosemary.

Currently a work day is being planned to remove some of the tall woody scrub plants that are shading the Etonia rosemary plants to give them a better chance at survival. Join us on March 16-17th, 2019 to help this plant thrive in its only protected home location, Etoniah Creek State Forest.

[1] For more about scrub you can read our short description here, FNAI's Natural Community account here, USFWS's factsheet here.
[2] Kral and McCartney. 1991. A new species of Conradina (Lamiaceae) from northeastern peninsular Florida. SIDA, Contributions to Botany Vol. 14, No. 3, pp. 391-39. https://www.jstor.org/stable/41966900
[3] The Putnam Land Conservancy and the Florida Native Plant Society are partners on the Warea Area Project. Watch a video short and read a blog post about the Warea Area.


Anonymous said…
Could this be a pollination issue? Are they self fertile? Also, is illegal collecting of plants/seeds a possibility.
The plants do set some viable seed but we have no quantitative data on what the seed set is, and how it varies during the flowering season. I have observed some nectar robbing by carpenter bees that damages flowers in the late fall.
There are no published data on self vs. out-crossing fertility rates, as far as I know.
Don’t know about theft. (Personally I seriously doubt people steal the plants. It isn't well known certainly among the horticulture community and the few native plant people who have actually seen it know enough not to collect it.)
Propagation would be a good thing IF careful attention is paid to genetic diversity. Taking cuttings from one or two plants as a tissue source, and using them to produce thousands of plants for “supplementing” the population, could actually be harmful by flooding the population with a single genotype— especially if they are self incompatible. - Mark Elliott (blog author)

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