Biology

Sewanee: The University of the South

Sewanee’s very own endangered species

June 12, 2013

 

When Clematis morefieldii was first discovered near a vacant lot in 1982 by botany student James Morefield (the plant’s namesake), it was thought to be endemic to Northern Alabama. Only five populations were found in the initial survey, some with only a few stunted plants, and the future of the bell-flowered vine looked bleak. Several of the existing populations, which were already in jeopardy due to their small size and highly specific habitat needs, were destroyed by residential development before state botanists could take more serious actions towards the protection of the species. Commonly known as Morefield’s leather flower or Huntsville vasevine, C. morefieldii was listed in 1992 as endangered across its range, which warranted some public attention (as many endangered species do) when a number of big development projects were brought to a screeching halt. Still, the plant received minimal attention from the botanical world, and it wasn’t until 2003 that a handful of populations were located in Southeast Tennessee, along the limestone bluffs of the Cumberland Plateau in Franklin and Grundy Counties. Now, in 2013, these sites (along with some of the original sites in Northern Alabama) seem to be the only remaining refuges for this rare but beautiful species.

This brings us to the most recent Sewanee Herbarium field adventure: a trek through the forest with state botanist Todd Crabtree in search of the Domain’s only endangered plant, none other than Clematis morefieldii. Todd, the leading expert on the species, shared some of his ideas about its mysterious dispersal mechanisms as we drove down Breakfield Road in his white jeep. He’s the first to admit that a great deal remains to be discovered in terms of the biology of the plant, yet we had no trouble finding it. His handheld GPS took us (after some scrambling up and down the bluff) straight to one of the plants he had recorded in a past survey of the Domain’s populations. Prior to this find, I had been under the impression that the exceedingly rare and federally listed vine would be a little more secretive, but let me tell you, this is not the case, at least not in the summer months. The pink, urn-like flowers are several centimeters long, dangling down from the woolly vine in groups of two. The blooms render the little plant quite conspicuous if you know where to look, but there’s the kicker: you have to know where to look.

State botanist Todd Crabtree counts the flowers of a Clematis morefieldii vine growing on a limestone bluff in Sewanee, TN.

State botanist Todd Crabtree counts the flowers of a Clematis morefieldii vine growing on a limestone bluff in Sewanee, TN.

Todd, no beginner at sniffing out C. morefieldii populations, pointed out species he considered to be indicative of the right type of habitat as we walked along the limestone layer on the South-facing side of the Plateau. “Taenidia intergerrima (yellow pimpernel), that’s a good sign,” he noted as we searched the seeps and rocky slopes above the bluff. The rarity of the tomentose (hairy) vine is partly due to the limited availability of its preferred habitat: bluff faces that are open enough to be sunlit but shaded enough to remain moist, and where there is plenty of rocky or shrubby substrate upon which it can attach its tendrils and climb. Todd explained that many of the populations he monitors in Franklin and Grundy counties seem to be struggling from lack of sunlight, which poses a complicated management issue. Cutting down surrounding shrubs to allow more light may benefit the plants, but you risk over-drying the soil and losing them altogether. This is but one of the many complications we face in the protection and management of C. morefieldii.

C. morefieldii leaves and immature fruiting structures

C. morefieldii leaves and immature fruiting structures

After successfully re-locating each of the previously known populations and recording data about their flowers and fruiting structures, we made our way back up the steep slope feeling satisfied with our findings. Thankfully, the Domain’s C. morefieldii are doing pretty well, and Todd will return for another visit in July to monitor the progress of fruits. The other populations, however, may not be so lucky. The available habitat for this species is already limited by intricate ecological factors, and new stone quarries and further residential development around Huntsville only exacerbate the problem. Additional threats stem from the natural world: deer browse (especially in Sewanee), insect herbivory on flowers, and the suppression of forest fires all contribute to C. morefieldii‘s struggle for survival. Todd mentioned a few possible solutions to these issues (deer exclosures, fire regimes, and intentional seed dispersal, to name a few), but to be effective in managing this species, we first must know much more about it (as of now, close to nothing is known about the plant’s biology). The mechanism of seed dispersal, for example, is unknown, yet this is a crucial bit of information- how can we aid the propagation of the species if we don’t understand it? Here lies an incredible opportunity for research.

“Our Clematis morefieldii populations have great scientific potential,” says Sewanee Herbarium director and conservation biology professor Dr. Jonathan Evans. “This is an excellent chance for students to engage with our very own endangered species, to make the connection between science and policy.” Research conducted by Sewanee students (in close conjunction with the Herbarium and state botanists) will help to uncover the unique life processes of this species and thus inform management decisions for the Domain and elsewhere. This is truly a win-win situation: a once-in-a-lifetime educational opportunity for ambitious undergraduate students, and a step forward for a little-known, federally endangered plant.

Hali Steinmann (EcoBio '15)

From the Sewanee Herbarium Blog 

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