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Maple-leaf oak (Quercus acerifolia) is a rare tree species commonly agreed to occur at just four sites in the world, all of which are in Arkansas. All of these sites are open, rocky woodlands on sandstone or novaculite substrate and are located at the tops of high-elevation ridges in the Arkansas Valley and Ouachita Mountains: Magazine Mountain in Logan County, Porter Mountain in Polk County, Pryor Mountain in Montgomery County, and Sugarloaf Mountain in Sebastian County.
The growth form of maple-leaf oak ranges from short, stunted multi-trunked shrubs to single-trunked trees up to fifty feet tall. It is most easily distinguished by its upper leaves, which are commonly as wide or wider than they are long, with three to five prominent lobes. They somewhat resemble the leaf shape of a sugar maple (Acer saccharum).
The taxonomic status of maple-leaf oak remains somewhat controversial. It was originally described by Palmer (1927) as a variety of Shumard oak (Quercus shumardii var. acerifolia) based on specimens he collected on Magazine Mountain in 1923, but it was later elevated to the species level by Stoynoff and Hess (1990). Others, including Ladd and Thomas (2015), have proposed that the extreme morphology of maple-leaf oak is likely environmentally induced, a consequence of extreme conditions at sites where it is found.
Botanists, including staff members of the Arkansas Natural Heritage Commission, have found populations of trees resembling maple-leaf oak at a number of other sites across the Ozark Plateau in both Arkansas and Missouri, in other regions of the Ouachita Mountains in Arkansas, and in at least one site in Tennessee. These trees, however, need additional study (including genetic analysis) to determine the extent to which environmental conditions influence morphology and to rule out other taxa, including Buckley’s oak (Quercus buckleyi) and Schneck’s oak (Quercus shumardii var. schneckii).
For additional information:Ladd, Douglas, and Justin R. Thomas. “Ecological Checklist of the Missouri Flora for Floristic Quality Assessment.” Phytoneuron 2015-12: 1–274. http://www.phytoneuron.net/2015Phytoneuron/12PhytoN-MissouriFlora.pdf (accessed June 16, 2016).
Palmer, Ernest J. “On Nuttall’s Trail through Arkansas.” Journal of the Arnold Arboretum 8 (1927): 25–55.
Stoynoff, Nick, and William J. Hess. “A New Status for Quercus shumardii var. acerifolia (Fagaceae).” Sida 14, no. 2 (1990): 267–271.
Theo Witsell Arkansas Natural Heritage Commission
Last Updated 10/13/2017
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