Southeastern Naturalist 419 D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 22001199 SOUTHEASTERN NATURALIST 1V8o(3l.) :1481,9 N–4o2. 93 Current Status of Tennessee Gladecress, Leavenworthia exigua var. lutea (Brassicaceae), in Alabama David M. Frings1,*, Lawrence J. Davenport1, Christopher Oberholster2, and Terry M. Hardig3 Abstract - The late-winter ephemeral Leavenworthia exigua var. lutea (Tennessee Gladecress; Brassicaceae), has historically been known from moist limestone and dolomite cedar glades in Tennessee and Alabama. Until this study, its distribution included only 8 glades in 6 counties of the Valley and Ridge, Appalachian Plateau, and Interior Low Plateau physiographic provinces in Alabama. During early spring of 2017, 2018, and 2019, we examined 26 Alabama glades for the presence of this very rare taxon. The historic populations in Jefferson and St. Clair counties of central Alabama have been extirpated by habitat destruction from urbanization. The population of L. exigua var. lutea reported from Colbert County (northwestern Alabama) could not be relocated, while that in Lawrence County (north-central Alabama) was found to be based on misidentified specimens of L. alabamica (Alabama Gladecress) with yellow flowers. This study documents 9 new records of L. exigua var. lutea in Shelby and Sumter counties, more than doubling the known populations in Alabama and extending its distribution into the Gulf Coastal Plain. Introduction Leavenworthia exigua Rollins var. lutea Rollins (Tennessee Gladecress; Brassicaceae), is a late-winter ephemeral, annual plant reported only from Tennessee and Alabama (Fig. 1; Rollins 1993, USDA 2019, Weakley 2015). Its preferred habitat is moist limestone or dolomite cedar glades and adjoining pastures and roadsides. Due to its varying morphology, L. exigua has been divided into as many as 3 varieties (Weakley 2015); other treatments (Al-Shehbaz and Beck 2010) maintain a single taxon. Because its yellow flowers form such an important trait—and one that can be confusing to its identification--we have retained “var. lutea” status for this taxon. Seeds of Leavenworthia exigua var. lutea germinate in autumn, forming tiny rosettes of pinnate leaves 3–6 cm long; while the terminal lobe is suborbicular, the 1–3 marginal lobes are shallowly dentate (Al-Shehbaz and Beck 2010). Flowering occurs from late February to mid-April; the 4 bright yellow spatulate petals, each 5–10 mm long, feature a small apical notch (Fig. 2). Unlike several related species, its fruits (siliques) are flat, oblong, and 1–2 cm long (Al-Sheh baz and Beck 2010). Petal color polymorphism has long been a point of confusion within the genus Leavenworthia (Lloyd 1969). In northern Alabama, some populations of 1Department of Biological and Environmental Sciences, Samford University, 800 Lakeshore Drive, Birmingham, AL 35229. 2Birmingham Audubon Society, 3720 4th Avenue S, Second Floor, Birmingham, AL 35222. 3Department of Biology, Chemistry and Mathematics, University of Montevallo, 75 College Drive, Montevallo, AL 35115. *Corresponding author - dmfrings@samford.edu. Manuscript Editor: Foster Levy Southeastern Naturalist D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 420 L. alabamica Rollins (Alabama Gladecress) are polymorphic for petal color, with some plants having pure yellow petals among its typical individuals (white petals with yellow centers). One purpose of this study was to verify the presence of “true” L. exigua var. lutea at its recorded locations in 6 Alabama counties: Bibb, Colbert, Jefferson, Lawrence, Marshall, and St. Clair (Keener et al. 2019). A second purpose was to locate and document “new” populations in Sumter and Shelby counties. Its potential presence in the latter was based on a 1989 conversation between C. Oberholster and Auburn University Professor Emeritus R.H. Mount, who remembered “yellow pasture mustards” from his tenure (during the 1960s) at the University of Montevallo. Methods We conducted this study during early spring (February through March) of 2017, 2018, and 2019. Methodology from 2 previous studies of Alabama glade plants (Frings and Davenport 2015, 2017) was utilized. We visited sites with reported L. exigua var. lutea populations to verify their presence (Fig. 3) and identified additional nearby glades using Google Earth® and geologic maps so that previously unknown populations could be discovered. We determined the location of each site using a global positioning device and recorded rock type, geologic formation, soil type, and soil pH. We collected soil Figure 1. Historic range of Leavenworthia exigua and its named varieties in the southeastern United States. Southeastern Naturalist 421 D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 Figure 2. Closeup of L. exigua var. lutea on Shoal Creek East Glade in Shelby County, AL. Figure 3. Chris Oberholster (left) and David Frings on Lady Tresses Glade, Bibb County, AL, 13 March 2017. Southeastern Naturalist D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 422 Figure 4. Current documented distribution of L. exigua var. lutea in Alabama. pH data in situ using an Oakton pH Spear™ similar in protocol to our previous studies on Alabama glades (Frings and Davenport 2015, 2017). Voucher specimens were collected and placed in the Samford University Herbarium (SAMF). We also examined specimens of previous collections; those herbarium acronyms are listed in Index Herbariorum (Thiers 2019). Results and Discussion We examined 26 limestone, dolomite, and chalk glades and adjacent pastures in 8 Alabama counties (Fig. 4) for the presence of L. exigua var. lutea; their key characteristics are recorded in Table 1. At sites supporting L. exigua var. lutea, soil pH varied from 6.83 to 8.05 (average = 7.93), indicating an affinity of the taxon for habitats with very alkaline soils that are derived from the carbonate rocks. A description of each (alphabetically by county) is included below. Bibb County - The “lost world” of Bibb County, AL, was discovered by Georgia botanist Jim Allison in 1992. This complex of small glades is now well known for its rare plants, including 7 new taxa and one that was previously considered extinct (Allison and Stevens 2001). Nearly 50 glades compose the Bibb County glade complex. In a report on 6 rare plant species for the US Fish and Wildlife Service, Allison (1993) noted that L.exigua var. lutea was found on 4 glades. In the present study, we verified Southeastern Naturalist 423 D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 Table 1. Field data and presence/absence of Leavenworthia exigua var. lutea in Alabama. Voucher specimens housed at SAMF. Location Province County Formation Rock Type Soil pH Present Voucher McCalla Glade Valley and Ridge Jefferson Conasauga Limestone - No - Leeds Glade Valley and Ridge St. Clair Newala Limestone - No - Lady Tresses Glade Valley and Ridge Bibb Ketona Dolomite 7.67 Yes Davenport 6474 Pratt Creek Glade Valley and Ridge Bibb Ketona Dolomite 8.05 Yes Davenport 6476 Small Glade Valley and Ridge Bibb Ketona Dolomite 7.66 Yes Davenport 6515 Westside Glade East Valley and Ridge Bibb Ketona Dolomite 7.57 Yes Davenport 6516 Eastside Glade Valley and Ridge Bibb Ketona Dolomite 7.65 Yes Davenport 6488 Desmond Glade Valley and Ridge Bibb Ketona Dolomite 7.7 No - Goat Glade Valley and Ridge Bibb Ketona Dolomite 7.56 No - Shoal Creek East Glade Valley and Ridge Shelby Conasauga Limestone 6.94 Yes Davenport 6476 Shoal Creek West Glade Valley and Ridge Shelby Conasauga Limestone 7.18 Yes Davenport 6477 The Cedars Glade Valley and Ridge Shelby Conasauga Limestone 7.18 Yes Davenport 6595 Shoal Creek South Glade Valley and Ridge Shelby Conasauga Limestone 7.21 Yes Davenport 6600 119 East Glade Valley and Ridge Shelby Conasauga Limestone 6.83 Yes Davenport 6597 Cedar Creek Glade Valley and Ridge Shelby Conasauga Limestone 7.28 Yes Davenport 6601 Access Road Glade Valley and Ridge Shelby Conasauga Limestone 7.24 Yes Davenport 6598 American Village Glade Valley and Ridge Shelby Conasauga Limestone 7.09 Yes Davenport 6596 Buck Island Glade Appalachian Plateau Marshall Leipers Limestone 7.73 Yes Davenport 6506 Tuscumbia Glade Interior Low Plateau Colbert Tuscumbia Limestone - No - Indian Tomb Hollow Glade Interior Low Plateau Lawrence Bangor Limestone - No - Roadside Glade Interior Low Plateau Lawrence Bangor Limestone 7.62 No - Prairie Grove Glade Interior Low Plateau Lawrence Bangor Limestone 7.69 No - Wetland Glade Interior Low Plateau Lawrence Bangor Limestone 7.54 No - Hidden Valley Glade Interior Low Plateau Lawrence Bangor Limestone 7.37 No - Isbell Glade Interior Low Plateau Lawrence Bangor Limestone 7.47 No - Fort Tombecbe Glade Gulf Coastal Plain Sumter Demopolis Chalk Chalk 8.00 Yes Davenport 6631 Southeastern Naturalist D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 424 that taxon’s presence at each of those glades. To make distance between glades more consistent, we separated Small Glade from the larger Westside Glade East noted by Allison, bringing the Bibb County total to 5. We also noted specific rock types at each glade studied. Since the time of Allison’s discoveries, the Bibb County glades (and their rare plants) have all been considered to be restricted to magnesium-rich Ketona Dolomite. Our preliminary studies (Frings and Davenport 2016) of these glades reveal a more complex geology which includes two calcium-rich dolomites (Bibb and Brierfield Formations). The 5 Bibb County Glades that contain L. exigua var. lutea are restricted to a small area near the junction of Pratt Creek and the Cahaba River. All 5 of these glades are, indeed, located on Ketona Dolomite near the contact of the Helena Thrust Fault, which places the carbonate rocks in contact with the younger Pennsylvanian age coal-bearing strata (Szabo et al. 1988). Colbert County - Despite 2 field trips (March 2017 and 2018) for this purpose, we were unable to relocate the Tuscumbia Glade population in northwest Alabama, where L. exigua var. lutea was collected in April 1996 (Spaulding & Whetstone 8782, AMAL; our examination of this single specimen confirmed its identification). We did, however, find a large population of L. alabamica at Hidden Valley Glade nearby. Both Tuscumbia and Hidden Valley Glades are located on Mississippian age Tuscumbia Limestone, which varies from a light-gray, fine- to very coarse-grained bioclastic limestone to an oolitic limestone near the top of the stratigraphic section (Szabo et al. 1988). Jefferson County - The Alabama Plant Atlas lists 4 vouchered specimens for L. exigua var. lutea, collected between 1941 and 1981, from a single site near Mc- Calla in western Jefferson County (Keener et al. 2019). The collecting site was described by the first collector, Roland Harper of the Geological Survey of Alabama, as “open calcareous flat woods” (Harper 3834, UNA). This glade most likely formed on Cambrian age Conasauga Limestone, which cropped out in what had been a large pasture north of McCalla (Szabo et al. 1988). The exponential growth of homes and businesses here since 1981 has destroyed these open pasture habitats and glades, leading to the species being extirpated from its 1 known locality in Jefferson County, AL. Lawrence County - Indian Tomb Hollow Glade is a small one, formed on Mississippian age Bangor Limestone, located on US Forest Service land in the Sipsey Wilderness, Bankhead National Forest, of northern Alabama. One collection of L. exigua var. lutea, collected in April 2005, has been cited from this site (Keener et al. 2019). Our examination of that specimen (Keener, Spaulding, & England 2619, AMAL) revealed it to be L. alabamica rather than L. exigua var. lutea. When walking across the site in March 2017, we noted that several individuals of L. alabamica there had pure yellow flowers rather than typical flowers with white petals and a yellow center (Fig. 5). Southeastern Naturalist 425 D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 We visited 4 additional glades in the Bangor Limestone region of Lawrence County during March and April 2017 to search for populations of L. exigua var. lutea (Table 1). Healthy populations of L. alabamica were observed on all of these glades, with no populations of L. exigua var. lutea. Marshall County - Leavenworthia exigua var. lutea was first collected in Marshall County (north-central Alabama) in April 1984 by Robert Kral (Kral 71146, VDB at BRIT, UWAL). On his labels, Kral described the population as being “abundant” on “both sides” of US 431 north of Guntersville, “on both TVA and Airport property”. What remains of this population is much reduced—a single grassy area along the entrance road to a TVA maintenance facility—due to highway widening and encroachment by Ligustrum sinense Lour. (Chinese Privet) and Pinus taeda L. (Loblolly Pine). This location is a cedar limestone glade formed of Ordovician age Leipers Limestone that crops out along the northwest limb of the Sequatchie Anticline. The Leipers is a medium dark-gray, thin- to medium-bedded, fossiliferous limestone with interbeds of thin argillaceous limestone (Szabo et al. 1988). At this location, several hundred specimens of L. uniflora (Michaux) Britton (Michaux’s Gladecress; Fig. 6) grew alongside L. exigua var. lutea, which numbered less than 100 plants. St. Clair County - Robert Kral made the single known St. Clair County collection of L. exigua var. lutea in 1973 (Kral 49445, VDB at BRIT, UWAL). He Figure 5. Leavenworthia alabamica showing the variation between white and yellow flowers at Indian Tomb Hollow Glade in Lawrence County, AL. Southeastern Naturalist D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 426 described the location as being 2 miles north of Leeds, AL, on AL 119. A search for glades in a wide area north of Leeds—both by satellite imagery and in the field— revealed no habitat that would currently support L. exigua var. lutea. The area along the AL 119 corridor has experienced rapid growth of retail and industrial development, destroying the open pastures and “limestone outcrop” described by Kral. Thus, we conclude that the sole St. Clair County population has been extirpated. Figure 6. Leavenworthia uniflora at Buck Island Glade in Marshall County, AL. Southeastern Naturalist 427 D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 Shelby County - The Shoal Creek Glades present a new county record for L. exigua var. lutea. These glades are formed on the Cambrian age Conasauga Limestone, which is a medium bluish-gray, fine-grained, thin-bedded argillaceous limestone. The glades are located in a newly dedicated park (based on former pasture land bordering Shoal Creek) owned by the City of Montevallo. Seven occupied glade areas have been documented within or near the park, with an eighth one to the north (within the American Village Citizenship Trust). Together, these 8 glades support populations of L. exigua var. lutea numbering in the thousands. Sumter County - While this study was being finalized, Jim Allison and Brian Keener apprised the authors of a previously unrecorded population of L. exigua var. lutea in Sumter County, AL. This extensive population occupies wet pasture land with no rock outcrops, underlain by Cretaceous age Demopolis Chalk, just west of Fort Tombecbe, an important archeological site on a bluff overlooking the Tombigbee River. The impervious chalk causes the thin veneer of black soil to become easily saturated, ponding shallow water during the winter months. The area is an active cattle ranch with evidence of grazing livestock. In spite of the cattle and invasive grasses, this population of L. exigua var. lutea appears quite healthy, covering 2–3 acres of wet pasture. This population is extremely significant, being the first known population of L. exigua var. lutea from Alabama’s Gulf Coastal Plain. Conclusions Our study shows that populations of L. exigua var. lutea are currently found in 4 counties in 4 different physiographic regions of Alabama (Table 1). Historical Figure 7. Populations of L. exigua var. lutea are often stressed by illegal dumping, as shown on Westside Glade East in Bibb County, AL. Southeastern Naturalist D.M. Frings, L.J. Davenport, C. Oberholster, and T.M. Hardig 2019 Vol. 18, No. 3 428 populations in Jefferson County (near McCalla) and St. Clair County (near Leeds) have been extirpated due to extensive residential and commercial development. While the current status of the Colbert County population is unknown, the Lawrence County population should be removed from the known distribution of the taxon due to misidentification. The Marshall County site, along US 431, has been much reduced due to urbanization. In contrast, the Bibb County populations of L. exigua var. lutea are robust. All populations recorded by Allison (1993) are still present, and few appear to be threatened. However, being situated on private property in isolated, rural areas, these populations remain at the whim of their landowners. One large glade, Westside Glade East, has long been used as a dump site for household trash (Fig. 7). Nine new populations in Shelby and Sumter counties have been added, more than doubling the total number of known extant Alabama populations. Six of the Shelby County populations occur on recently dedicated public property, destined to be a park for the City of Montevallo. One small population nearby, on private land, has been nearly extirpated by herbicide spray. Fortunately, one of the authors (T.M. Hardig) is working with the Mayor of Montevallo to assure the preservation of these populations. The recently recorded Sumter County population reveals the presence of L. exigua var. lutea in Alabama’s Gulf Coastal Plain. More populations may exist in open pasture lands—unassociated with rock outcrops—of surrounding, chalkbased areas. Outside of the above 5 Alabama counties, L. exigua var. lutea is only recorded from Bedford and Maury counties, TN (Chester et al. 1997). The recent Guide to the Vascular Plants of Tennessee (Tennessee Flora Committee 2015) lists the taxon as “possibly extirpated” from that state, leaving it—despite its common name—as an Alabama endemic. Acknowledgments The Jim Allison reports were shared with us by Tom Diggs, and we are grateful to both individuals for that critical information. Bob Mount, Jim Allison, and Brian Keener pointed us toward the Shelby and Sumter county populations. We also thank our 2 reviewers for their helpful comments, the landowners involved, and the City of Montevallo. Literature Cited Allison, J.R. 1993. Status of three federally listed plants (Marshallia mohrii, Spigelia gentianoides, Xyris tennesseensis) in Bibb County, Alabama. 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