Southeastern Naturalist 331 P.S. Lynch and W.B. Zomlefer 22001166 SOUTHEASTERN NATURALIST 1V5o(2l.) :1353,1 N–3o4. 52 Vascular Plant Flora of the South Atlantic Coastal Plain Limestone Forest: A Globally Imperiled Association Endemic to Central Georgia Patrick S. Lynch1,2 and Wendy B. Zomlefer1,* Abstract - The South Atlantic Coastal Plain Limestone Forest is a globally imperiled (G2) association restricted to the upper Coastal Plain of central Georgia. We conducted a comprehensive floristic inventory of this unique forest type during 2008–2011 at 7 sites (total of 44.67 ha [110.60 ac]) in Houston, Bleckley and Twiggs counties. The survey documented 336 vascular plant species in 98 families. The largest families were Asteraceae (28 spp.), Cyperaceae (22 spp.), Poaceae (19 spp.), Fabaceae (17 spp.), Rosaceae (16 spp.), and Fagaceae (14 spp.). Only 4.2% of this flora was non-native. Seventeen species were listed as rare, including the federally endangered Silene catesbaei. We provide a vouchered plant checklist for this association and general descriptions of the 3 main vegetation communities: uplands, slopes, and bottomlands. Introduction Calcareous forest communities of the southeastern Coastal Plain include several distinct forest associations (often rare) and are restricted to discontinuous areas from southern Arkansas and north-central Louisiana to South Carolina (Hill 1992, Morris et al. 1993). These predominantly hardwood forests occur on marinederived calcareous sands, clay, and limestone formations of the lower Tertiary, deposited when much of the area was covered by a shallow sea (Huddlestun 1993; Huddlestun and Hetrick 1978, 1986). The floristic diversity of these associations comprises calciphilic vegetation and species from adjacent forest communities and often also includes many rare, threatened and/or disjunct taxa (Edwards et al. 2013, Monk 1965, Wharton 1978). The South Atlantic Coastal Plain Limestone Forest (SACPLF) association is a globally imperiled (G2) calcareous forest type restricted to the upper Coastal Plain of central Georgia along the Ocmulgee River corridor between Warner Robins and Hawkinsville (Fig. 1; Govus 2008). The least-disturbed sites are located within or near Oaky Woods Wildlife Management Area (WMA) in Houston County and Ocmulgee WMA in Twiggs, Bleckley, and Pulaski counties. These oak–hickorydominated forest communities are underlain by a complex calcareous substrate of sand, clay, and limestone formations of the late Eocene and early Oligocene, and occupy north- and east-facing slopes and adjacent bottomlands along small stream tributaries (Edwards et al. 2013, Govus 2008). The sites frequently occur in association with the rare Georgia Eocene Chalk Prairies (Echols 2007, Echols et al. 1Department of Plant Biology, University of Georgia, Athens, GA 30602-7271. 2Current address - 233 Cross Road, Colquitt, GA 39837. *Corresponding author - wendyz@uga.edu. Manuscript Editor: Scott Markwith Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 332 2008) and are typically surrounded by beech-magnolia-dominated slope forests (hammocks; Wharton 1978) and fire-adapted upland mixed pine-hardwoods. The SAPCLF association is a variant of the Coastal Plain mesic slope-forest group detailed in Natural Communities of Georgia (Edwards et al. 2013). The NatureServe description of this association, Quercus muehlenbergii–(Quercus sinuata)–Carya spp./Sabal minor/Carex cherokeensis–Chasmanthium sessiliflorum (CEGL004023; Govus 2008), was based on a list of 49 woody and herbaceous species from 1 plot at each of 4 sites for the Georgia Department of Natural Resources (GA-DNR, Social Circle, GA, unpubl. data). The first author Figure 1. Map of the location of the 7 research sites in central Georgia. Dark gray = Oaky Woods WMA (includes lands owned and leased by GA-DNR) and light gray = Ocmulgee WMA. Circled numbers = study sites (see Table 1 for centroid coordinates); dashed lines and Ocmulgee River = county boundaries. Map based on GA-DNR (2011b) and Georgia GIS Clearinghouse (2014). Inset map of Georgia: shaded area = Bleckley, Houston, Pulaski, and Twiggs counties. Modified by S. Hughes and W. Zomlefer from Lynch (2012). Southeastern Naturalist 333 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 utilized a combination of transect-based field-sampling techniques and multivariate analyses to define localized plant communities comprising the SACPLF (Lynch 2012, Lynch et al. 2016). The results generally supported the NatureServe concept of the association but suggested Carex superata as a more appropriate representative species than Chasmanthium sessiliflorum for the herbaceous stratum. Cluster analysis of vegetation and cover data also resolved 3 distinct vegetation units for the SACPLF association—upland, slope, and bottomland— following a generalized hillslope model (Fig. 2). These findings were supported by data on soil-moisture content and degree of inclination, correlated with other edaphic factors, and certain indicator species. A plot-sampling study (Lynch 2012, Lynch et al. 2016) was conducted in conjunction with a floristic inventory of the general SACPLF area. The objectives of the plant-survey portion of the project, presented herein, were to: (1) provide a comprehensive plant species list for the SACPLF documented by voucher specimens, and (2) characterize the floristics of the 3 general hillslope vegetation communities of this little-studied and rare forest association. Methods Field site description P.S. Lynch used field reports provided by the GA-DNR (Govus 2008) and USGS topographic/geologic maps and satellite imagery (see Lynch 2012) to select 7 sites totaling 44.67 ha (110.60 ac) located in Oaky Woods WMA (Houston County, sites 1–4), Ocmulgee WMA (Bleckley County, site 6), and on private property (Houston and Twiggs counties; sites 5 [leased by GA-DNR] and 7, respectively) (Table 1, Fig. 1). Sites 2 (Houston County) and 5 (Twiggs County) were previously unknown to the GA-DNR and were discovered by P. Lynch. Figure 2. Diagram of the hillslope model for the SACPLF association showing structure and topological designations. Depth of calcareous substrate and proximity to soil surface vary locally. Modified by C. Kraus and W. Zomlefer from Lynch (2012). Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 334 Plant sampling and identification We made over 100 trips to the research sites for this inventory between 10 November 2008 and 21 October 2011. We collected plant specimens in duplicate whenever possible using standard field and herbarium techniques with permission from the GA-DNR and private landowners. We documented the flora of the SACPLF sites with a total of 760 voucher specimens. P. Lynch collected 462 numbered vouchers (intermittent numbers within the series Lynch 1-1420) for the general survey, plus 266 unnumbered specimens (Lynch s.n.) during concurrent transect-based sampling for a multivariate-analysis study (see Lynch 2012; Lynch et al. 2016). W.B. Zomlefer contributed a supplemental set of 32 specimens (Zomlefer 2440–2471). A complete set of vouchers has been deposited at the University of Georgia herbarium (GA), and a duplicate set at the Valdosta State University, Valdosta, GA, herbarium (VSC). P.S. Lynch identified the plant specimens using Weakley (2011), supplemented by Bailey (1951), Cronquist (1980), Gleason and Cronquist (1991), Isely (1990), Jones (2005), Radford et al. (1968), Wunderlin and Hansen (2011), and appropriate volumes of the Flora of North America (FNA, 1993+). Species nomenclature and designation of exotic species follow Weakley (2011); common names are from Weakley (2011) when available, supplemented by the PLANTS database (USDANRCS 2015). Standard authority abbreviations are from the Tropicos® (2015) database. Angiosperm family delineation follows APG III (2009). Results The floristic inventory yielded 336 vascular plant taxa (338 species and varieties) representing 218 genera in 98 families. For a complete annotated list of vascular plants, see Supplemental File 1, available online at http://www.eaglehill. us/SENAonline/suppl-files/s15-2-S2253-Zomlefer-s1, and, for BioOne subscribers, at http://dx.doi.org/10.1656/S2253.s1 . The annotated list is divided into ferns (11 species), gymnosperms (3 species) and angiosperms (322 spp.) and arranged alphabetically by genus and species. Table 2 (rare plants), Table 3 (exotic species), and Appendix 1 list the scientific names, authorities, and common names for species discussed in this paper. Table 1. Location and size of study sites. See Figure 1 for map of the sites. * = site discovered by P.S. Lynch (previously unknown to the GA-DNR). Research-site location datum = WGS84. Community type: B = bottomland, S = slope, and U = upland. Site County Area ha (ac) Centroid (latitude, longitude) Community type(s) 1 Houston 3.72 (9.19) 32.4889185°N, 83.5464886W° U 2* Houston 5.76 (14.24) 32.4924521°N, 83.5416661W° B, U 3 Houston 7.41 (18.31) 32.4660936°N, 83.5599903W° B, S 4 Houston 6.52 (16.10) 32.4999787°N, 83.5290053W° B, S 5* Houston 3.89 (9.61) 32.5066596°N, 83.5575764W° B, S, U 6 Bleckley 12.05 (29.79) 32.4200799°N, 83.4684788W° B, U 7 Twiggs 5.41 (13.36) 32.5038000°N, 83.4802790W° B, S, U Southeastern Naturalist 335 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 Discussion Floristics Plants in the Asteraceae (aster family; 28 spp., 8.3%) accounted for the largest percent of total species richness of the SACPLF, followed by Cyperaceae (sedge family; 22 spp., 6.5%), Poaceae (grass family; 19 spp., 5.6%), Fabaceae (legume family; 17 spp., 5.0%), Rosaceae (rose family; 16 spp., 4.7%), and Fagaceae (beech family; 14 spp., 4.2%). All other families comprised less than 3% of the total species. According to the University of Georgia and Valdosta State University herbaria records, the survey documented 282 new county records for Bleckley (98 Table 2. The 17 rare plant species documented in this study from the South Atlantic Coastal Plain Limestone Forest. State status: E = endangered (critically imperiled), and T = threatened (likely to become endangered). Federal status: LE = endangered (critically imperiled). Rank: G = global rank, S = state rank; 1 = critically imperiled (very high risk of extirpation), 2 = imperiled (high risk of extirpation), 3 = vulnerable (moderate risk of extirpation), 4 = apparently secure, 5 = secure, and ? = inexact numeric rank (GA-DNR 2015, USFWS 2015). Counties: B = Bleckley, H = Houston, T = Twiggs; † = county record according to herbarium collections at the University of Georgia and Valdosta State University. Community types: B = bottomland, S = slope, and U = upland. For site locations, see Table 1 and Figure 1. State/federal status; Site(s); Community Species (Common name) state/global rank (County) type(s) Asplenium heteroresiliens W.H. Wagner T/—; S1/G2 3; (H†) S (Marl Spleenwort) Carex floridana Schwein. (Florida Sedge) —/—; S3/G5? 7; (T†) S Cayaponia quinqueloba (Raf.) Shinners —/—; S2/G4 4; (H) B (Fivelobe Cucumber) Crataegus calpodendron (Ehrh.) Medik. —/—; S2?/G5 3; (H†) S (Pear Hawthorn) Crataegus triflora Chapm. (Threeflower T/—; S1/G2G3 1, 2; (H) B, U Hawthorn) Hypericum tubulosum Walter (Southern —/—; S1S3/G4? 7; (T†) B Marsh St.-John’s-wort) Matelea flavidula (Chapm.) Woodson —/—; S3?/G3? 4; (H) U (Yellow Spinypod) Ophioglossum engelmannii Prantl —/—; S2S3/G5 4; (H) U (Limestone Adder’s Tongue) Panax quinquefolius L. (Ginseng) —/—; S3/G3G4 3; (H) S Ponthieva racemosa (Walter) Mohr —/—; S2?/G4G5 2; (H†) B (Shadow Witch) Quercus sinuata Walter var. sinuata —/—; S1S2/G4G5 2, 6, 7; (B†, H, T†) B (Bastard Oak) Scutellaria ocmulgee Small (Ocmulgee T/—; S2/G2 5, 7; (H†, T†) S Skullcap) Silene catesbaei Walter (Fringed Campion) E/LE; S2/G2 2; (H) B Smilax lasioneura Hook. (Midwestern —/—; S2?/G5 3, 5, 6; (B†, H) B, S, U Carrionflower) Tragia cordata Michx. (Heartleaf Noseburn) —/—; S2?/G4 2; (H) B Trillium lancifolium Raf. (Lanceleaf Trillium) —/—; S3/G3 4; (H) B Vicia minutiflora D. Dietr. (Smallflower Vetch) —/—; S1?/G5 3, 5, 6, 7; (B†, H, T†) B Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 336 spp.), Houston (95 spp.), and Twiggs (89 spp.) counties; these species are indicated by a † in the annotated list of vascular plants. Rare species. Table 2 lists the 17 rare species (GA-DNR 2015) for which we collected voucher specimens from the study sites. Vouchers of 9 species represent new records for Bleckley (3 spp.), Houston (4 spp.), and Twiggs (5 spp.) counties (indicated by a † in Table 2). Four rare species—Asplenium heteroresiliens, Crataegus triflora, Scutellaria ocmulgee, and Silene catesbaei are protected. Silene catesbaei is state- and federally listed as endangered, a critically imperiled species in danger of extinction (USFWS 2015). The 3 other protected species have a state status of threatened (likely to become endangered; GA-DNR 2015). Silene catesbaei and Crataegus triflora were vouchered from site 2 (Houston County), where they were growing in a slightly elevated and drier area of the bottomland characterized by mesic soils with a relatively high pH (~6.4-6.8; Lynch et al. 2016). The ~12 plants in the Silene catesbaei population were scattered along the drainage area. P.S. Lynch also vouchered Crataegus triflora from the uplands of site 1 where it occurred upslope in the adjoining remnant Georgia Eocene Chalk Prairie (Echols 2008). The species was a subcanopy indicator for portions of the bottomland community (Lynch et al. 2016). However, these shrubby trees were all mature (i.e., no seedlings or saplings present), suggesting that regeneration of the species may be limited at this site (Lynch 2012). A population of Asplenium heteroresiliens was well established along the slopes of site 3 (Houston County) upon limestone outcrops, where it was competing with the invasive Lonicera japonica Thunb. (P. Lynch, pers. observ.). According to the Table 3. The 14 exotic plant species documented in this study from the South Atlantic Coastal Plain Limestone Forest. Non-native status follows Weakley (2011). Invasive-category rank for Georgia natural areas, applicable to 8 species: 1 = serious threat, extensively invades native plant communities; 2 = moderate threat; and 3 = minor threat or a threat in adjacent states (GA-EPPC 2006). Community types: B = bottomland, S = slope, and U = upland. See Table 1 and Figure 2 for site locations. Bidens bipinnata L. (Spanish Needles) is listed by the GA-EPPC (2006) as an exotic invasive; however, ITIS (2015), Weakley (2011), and Wunderlin and Hansen (2011) list it as a native plant, and so we do not include it here. Invasive Community Species (Common name) category rank Site(s) type(s) Albizia julibrissin Durazz. (Mimosa) 1 1 U Cardamine hirsuta L. (Hairy Bittercress) - 6 U Deparia petersenii (Kunze) M. Kato (Japanese False Spleenwort) - 6 B Elaeagnus pungens Thunb. (Autumn Silverberry) 2 2 B Elaeagnus umbellata Thunb. (Autumn-olive) 1 1 U Ligustrum japonicum Thunb. (Japanese Privet) 2 5 S Ligustrum sinense Lour. (Chinese Privet) 1 7 B Liriope muscari (Decne.) L.H. Bailey (Liriope) 3 6 U Lonicera japonica Thunb. (Japanese Honeysuckle) 1 4 S Maclura pomifera (Raf.) C.K. Schneid. (Osage-orange) - 2 B Microstegium vimineum (Trin.) A. Camus (Japanese Stilt-grass) 1 7 B Potentilla indica (Andrews) T. Wolf (Indian-strawberry) - 4 B Stellaria media (L.) Vill. (Common Chickweed) - 4, 6 S, U Youngia japonica (L.) DC. (Asiatic Hawk’s-beard) - 6 B Southeastern Naturalist 337 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 collections at the University of Georgia and Valdosta State University herbaria, this species had been vouchered only once previously from Georgia (Lee County, Thorne & Muenscher 8427, GA) in 1948. The first author collected Scutellaria ocmulgee, a species endemic to central Georgia and southern South Carolina (Weakley 2011), from sandy, dry areas along the slopes of sites 5 (Houston County) and 7 (Twiggs County). The species had previously been documented only from Bibb County, also in central Georgia (Allison 3612, Moore 1286, GA). Two other rare species merit mention. Quercus sinuata var. sinuata, state-ranked as imperiled (S1S2; Table 2) and vouchered from 3 sites (2, 6, 7), was a characteristic canopy species indicative of high-quality bottomlands in the SACPLF (Lynch et al. 2016). All individuals in these areas were mature trees (canopy-size class), and no seedlings or juveniles were present in the understory strata. Vicia minutiflora has a state rank of S1?, possibly critically imperiled. Multivariate analyses (Lynch 2012, Lynch et al. 2016) categorized this rare species as an indicator for the SACPLF, where it was common in the uplands and bottomlands in all study areas (P. Lynch, pers. observ.) and vouchered from the bottomlands at 4 sites. Exotic species. The inventory of the SACPLF documented 14 non-native species (Table 3), representing only 4.2% of the total flora. This total is a relatively low number of exotic species, especially compared to the 10.5% exotics (37 spp.) for the flora of the associated Georgia Eocene Chalk Prairie (Echols and Zomlefer 2010). Eight of these SACPLF non-natives are listed as invasive in the state according to the Georgia Exotic Pest Plant Council (GA-EPPC 2006) and ranked in 3 categories according to potential threat to native species (Table 3). Five of these invasive-ranked species—Albizia julibrissin, Elaeagnus umbellata, Ligustrum sinense, Lonicera japonica, and Microstegium vimineum—are Category 1, the most serious threat and having the greatest potential to extensively invade native plant communities. However, Lonicera japonica was the only exotic species significantly displacing native flora at all 7 sites (Lynch 2012). The plants, typically spreading vegetatively in the study areas, were relatively infrequent in the late seral-stage forests of the SACPLF, but dominated the seedling and herbaceous layers in recently disturbed areas (Lynch et al. 2016). Ligustrum sinense and Microstegium vimineum occurred relatively infrequently in the SACPLF and were largely limited to riparian areas in wind-throw or anthropogenically created canopy gaps (Lynch 2012). Albizia julibrissin and Elaeagnus umbellata were infrequent and vouchered only from the upland of site 1, where they were restricted to disturbed ecotonal zones along the periphery of the forest. P.S. Lynch vouchered the other 3 invasive exotic species—Elaeagnus pungens (Category 2, moderate threat), Ligustrum japonicum (Category 2), and Liriope muscari (Category 3, minor threat or a threat in adjacent states)—from 1 site each. These species were also limited in number and very restricted in habitat within the SACPLF; thus, they currently present little threat. The 6 remaining exotic species are not ranked as invasive (Table 3), occurred in few sites, and were typically infrequent to rare in occurrence at any study site (for the annotated list of vascular Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 338 plants, see Supplemental File 1, available online at https://www.eaglehill.us/ SENAonline/suppl-files/s15-2-S2253-Zomlefer-s1, and, for BioOne subscribers, at http://dx.doi.org/10.1656/S2253.s1). Vegetation communities The SACPLF has been generally classified as an oak-hickory forest (Edwards et al. 2013), and this survey documented 13 oak and 6 hickory species as canopy dominants (with other deciduous hardwoods, outlined here). Below are general descriptions of the 3 main community types present within the SACPLF: uplands, slopes, and bottomlands (Fig. 2). Species composition can vary among these communities, depending on the location and history of anthropogenic disturbance. Upland community. The upland community type of the SACPLF occurs on north- and east-facing slopes with a moderate incline (inclination mean = 15.9 ± 1.3 %; Lynch et al. 2016). The sandy loam soils are submesic and subacidic (mean pH = 5.92 ± 0.15), vary in depth (~15–100 cm), and are underlain by clay or clay loams that are exposed along small gullies (Lynch 2012, Woods 1967). The canopy of the upland is a diverse mix of oaks and hickories. Quercus muehlenbergii is a characteristic and codominant species, typically with Q. alba, Q. nigra, Q. pagoda, Q. velutina, Carya carolinae-septentrionalis, C. cordiformis, C. glabra, and C. ovata. In disturbed sites, Liquidambar styraciflua is also abundant in this stratum (Lynch 2012, Lynch et al. 2016). Subcanopy species include Morus rubra, Ostrya virginiana, Vitis rotundifolia, and V. vulpina. The composition of the shrub layer varies with disturbance history and may include species such as Callicarpa americana and Crataegus triflora (Lynch et al. 2016). Bromus pubescens, Carex superata, Dichanthelium boscii, Polystichum acrostichoides, Sanicula canadensis, and Vicia minutiflora are common understory species (Lynch and Zomlefer 2014). Common spring ephemerals in this layer include Sanguinaria canadensis, Sanicula odorata, Trillium underwoodii, and Yeatesia viridiflora. Slope community. Like the uplands, the SACPLF association slope community occurs on north- and east-facing slopes on thin loams over unconsolidated limestone deposits (Woods 1967). However, the incline is much steeper (inclination mean = 27.9 ± 4.2%, maximum 57.8%), and the soils are less acidic (mean pH = 6.30 ± 0.16) and more mesic than those of the uplands (Lynch et al. 2016). The habitat along the slopes gradually transitions from the exposed, well drained, and subacidic shoulderslopes to the more sheltered, mesic, and circumneutral backslopes and toeslopes (Fig. 2). The shift in the composition of the flora along the slope reflects these gradients in local environmental conditions . The variable canopy on the slopes generally includes Quercus muehlenbergii and Tilia americana var. heterophylla with other species such as Carya cordiformis, C. ovata, and Quercus michauxii. Subcanopy species Fraxinus americana and Ostrya virginiana dominate the locally drier subacidic shoulderslopes, transitioning to Acer floridanum in more mesic areas along the lower backslopes (Lynch et al. 2016). Aesculus pavia and Ptelea trifoliata codominate in the shrub layer along the more exposed shoulderslopes and upper backslopes. These 2 species are replaced Southeastern Naturalist 339 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 by Philadelphus inodorus and Rhapidophyllum hystrix at the lower backslope and toeslope positions, particularly on shallow soils on narrow limestone ledges (Lynch and Zomlefer 2014). The shoulderslopes (Fig. 2) support an understory stratum similar to the adjoining upland community, but frequently with additional unusual species such as Brintonia discoidea and Collinsonia canadensis. Downslope, Carex superata is often a dominant herbaceous species (as in the uplands) with Sanicula odorata and Yeatesia viridiflora (Lynch et al. 2016). The ephemeral spring flora of the slopes typically includes Erythronium umbilicatum, Maianthemum racemosum, Polygonatum biflorum, Thalictrum thalictroides, and Trillium underwoodii, as well as the locally rare T. maculatum. Bottomland community. The SACPLF association bottomlands are infrequently flooded and generally occur on subacidic to basic wet clay-loam soils (Smith and Rigdon 2003; Woods 1963, 1967). In areas with brief periodic inundation and extensive scouring, the removal of organic debris exposes the more acidic (mean pH = 5.80 ± 0.13), mineral-deficient clay subsoil (Lynch and Zomlefer 2014, Lynch et al. 2016). However, sediment accumulation downslope from calcareous outcroppings is significant in SACPLF bottomlands with less intermittent flooding. In these areas, the basic (mean pH = 6.79 ± 0.14) and mineral-rich black loam soils typically support climax SACPLF bottomland communities (Lynch et al. 2016). The canopy of the bottomland is characterized by several oak species (e.g., Quercus nigra, Q. lyrata, Q. michauxii, Q. pagoda, Q. shumardii, Q. sinuata var. sinuata, and hickory (e.g., Carya ovata and C. glabra). Codominants include Celtis laevigata, Fraxinus pennsylvanica, Juglans nigra, Liquidambar styraciflua, Ulmus americana, and U. rubra. The subcanopy, often distinctly stratified, is dominated by Acer floridanum, and Carpinus caroliniana becomes more prevalent in more mineral-deficient areas subject to intermittent flooding and scou ring. The shrub layer of the SACPLF bottomland is generally characterized by Asimina triloba, Cercis canadensis, Cornus asperifolia, Lindera benzoin, Rhapidophyllum hystrix, Sabal minor, and Viburnum prunifolium. A pronounced shift in species composition of this stratum is correlated with the amount of scouring and/or sediment accumulation in the slope-bottomland transitional zone (Lynch et al. 2016). For example, Lindera benzoin is the dominant species in narrow (~5–10 m wide), heavily scoured areas in late-successional, closed-canopy bottomland. Cornus asperifolia dominates substrates of significant colluvial deposition, while Sabal minor is more common on the subacidic and mineraldeficient heavy clay soils. The understory of the SACPLF bottomland is very diverse and dominated by Carex cherokeensis, which may carpet the ground (Lynch and Zomlefer 2014). Other common species are Arundinaria gigantea, Hylodesmum pauciflorum, Symphyotrichum urophyllum, and Yeatesia viridiflora. Common vines in this stratum include Calycocarpum lyonii, Menispermum canadense, Passiflora lutea, and Smilax lasioneura (state-ranked possibly imperiled). The spring ephemeral flora is characterized by Vicia minutiflora (state-ranked as possibly critically Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 340 imperiled), Zephyranthes atamasca, and 2 Southeastern endemic Trillium species, the rare T. lancifolium (state-ranked as vulnerable) and another tentatively identified as T. decumbens (Lynch 2012, Lynch and Zomefer 2014), typically a Ridge and Valley species and disjunct in Houston County. However, genetic analyses currently underway indicate that this population likely represents a new taxon (under study by E. Schilling, University of Tennessee, Knoxville, TN, and T. Patrick, GA-DNR, Social Circle, GA, pers. comm.). The bottomland harbors several other rare species (Table 2), including Ponthieva racemosa (possibly imperiled) and Silene catesbaei (endangered). Conclusions This first floristic inventory of the SACPLF documented 17 rare species and 282 county records for 3 counties, and allowed description of the main vegetation communities. The survey may thus serve as a baseline for identification of this unusual forest association and its unique flora. In addition, 2 new occurrences of the SACPLF were discovered by the first author for this study. We recommend that future inventory efforts should concentrate on locating new sites and securing the locations of rare species. Several relatively pristine examples of the SACPLF have been preserved by recent acquisition of ~4050 ha (~10,000 acres) of Oaky Woods WMA by the state (GA-DNR 2011a). However, other high-quality tracts on private property remain vulnerable to habitat degradation and destruction through logging and residential encroachment (Edwards et al. 2013). A comprehensive approach is needed to ensure long-term preservation of the SACPLF, which would involve apprising private landowners of conservation opportunities for this endemic forest, and encouraging collaboration with appropriate governmental agencies and other conservancy groups. We hope that this research will assist ongoing conservation efforts throughout the area and aid in the preservation efforts of this rare forest association. Acknowledgments We are indebted to James L. Hamrick who directed P. Lynch during the writing phase for his Master’s thesis about this research. The authors thank Tom Patrick (Georgia Department of Natural Resources) for introducing us to this community and for providing valuable insights, field assistance, and commentary on Trillium species found at these sites. We also acknowledge other GA-DNR personnel: Bobby Bond, Matt Elliott, Raye Jones, and Randy Wood. Randy and Raye shared their extensive knowledge of the area; Bobby scheduled visits; and Matt helped identify research sites and provided funding. The following individuals generously granted access to their property: Mr. and Mrs. Gary J. Black, Joan Grantham, Keith Holcomb, James Howard Jr., Thomas Hunt Jr., Plum Creek Timber Company, and Kelvin Seagraves. Land managers Keith Barnes and Ben Lindsey also allowed survey of their properties. Sharon Mozley-Standridge and Zach Standridge graciously furnished accommodations for P. Lynch during field work; Glenn Galau, Chris Graham, Kristian Jones, and Brenda Wichmann assisted in the field; David E. Giannasi, and Laura Lukas helped with some plant identifications; Ron W. Lance verified the Crataegus determinations; Dan Spaulding annotated the Lobelia specimens; Edward Schilling provided updates on the new Southeastern Naturalist 341 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 taxon of Trillium from Houston County; Steven Hughes prepared the base map for Figure 1; and Carmen Kraus redrafted Figure 2. Funding for this study was provided to P. Lynch by the Georgia Botanical Society (Marie Mellinger Field Botany Research Grant), Georgia Native Plant Society (Jeane Reeves Research Grant), GA-DNR (Wildlife Resources Division), and Department of Plant Biology, University of Georgia (Palfrey Grant for Graduate Student Research). Literature Cited Angiosperm Phylogeny Group III (APG III). 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161:105–121. Bailey, L.H. 1951. 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University Press of Florida, Gainesville, FL. 783 pp. Southeastern Naturalist P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 344 Appendix 1. Scientific names, authorities, and common names for species discussed in this paper, except for rare plants (Table 2) and exotic species (Table 3). Species nomenclature follows Weakley (2011); standard authority abbreviations are from the Tropicos® (2015) database; and common names are from Weakley (2011) when available, supplemented by the PLANTS database (USDA-NRCS 2015). Scientific name with authority Common name Acer floridanum (Chapm.) Pax Southern Sugar Maple Aesculus pavia L. Red Buckeye Arundinaria gigantea (Walter) Muhl. Giant Cane Asimina triloba (L.) Dunal Common Pawpaw Brintonia discoidea (Elliott) Greene Rayless Mock-goldenrod Bromus pubescens Muhl. ex Willd. Common Eastern Brome Callicarpa americana L. Beautyberry Carex cherokeensis Schwein. Cherokee Sedge Carex superata Naczi, Reznicek & B.A. Ford Willdenow’s Sedge Carpinus caroliniana Walter American Hornbeam Carya carolinae-septentrionalis (Ashe) Engl. & Graebn. Southern Shagbark Hickory Carya cordiformis (Wangenh.) K. Koch Bitternut Hickory Carya glabra (Mill.) Sweet Pignut Hickory Carya ovata (Mill.) K. Koch Common Shagbark Hickory Celtis laevigata Willd. Sugarberry Cercis canadensis L. Eastern Redbud Chasmanthium sessiliflorum (Poir.) Yates Longleaf Spikegrass Collinsonia canadensis L. Northern Horsebalm Cornus asperifolia Michx. Eastern Roughleaf Dogwood Dichanthelium boscii (Poir.) Gould & C.A. Clark Bosc’s Witchgrass Erythronium umbilicatum Parks & Hardin Dimpled Trout Lily Fraxinus americana L. White Ash Fraxinus pennsylvanica Marshall Green Ash Hylodesmum pauciflorum (Nutt.) H. Ohashi & R.R. Mill Few-flowered Tick-trefoil Juglans nigra L. Black Walnut Lindera benzoin (L.) Blume Northern Spicebush Liquidambar styraciflua L. Sweetgum Maianthemum racemosum (L.) Link False Solomon’s-seal Menispermum canadense L. Moonseed Morus rubra L. Red Mulberry Ostrya virginiana (Mill.) K. Koch Hop-hornbeam Passiflora lutea L. Eastern Yellow Passionflower Philadelphus inodorus L. Appalachian Mock-orange Polygonatum biflorum (Walter) Elliott Small Solomon’s-seal Polystichum acrostichoides (Michx.) Schott Christmas Fern Ptelea trifoliata L. Hop-tree Quercus alba L. White Oak Quercus lyrata Walter Overcup Oak Quercus michauxii Nutt. Swamp Chestnut Oak Quercus muehlenbergii Engelm. Chinquapin Oak Quercus nigra L. Water Oak Southeastern Naturalist 345 P.S. Lynch and W.B. Zomlefer 2016 Vol. 15, No. 2 Scientific name with authority Common name Quercus pagoda Raf. Cherrybark Oak Quercus shumardii Buckley Shumard Oak Quercus sinuata Walter var. sinuata Bastard Oak Quercus velutina Lam. Black Oak Rhapidophyllum hystrix (Pursh) H. Wendl. & Drude Needle Palm Sabal minor (Jacq.) Pers. Dwarf Palmetto Sanguinaria canadensis L. Bloodroot Sanicula canadensis L. Black Snakeroot Sanicula odorata (Raf.) K.M. Pryer & L.R. Phillippe Clustered Snakeroot Symphyotrichum urophyllum (Lindl. ex DC.) G.L. Nesom White Arrowleaf Aster Thalictrum thalictroides (L.) Eames & Boivin Rue-anemone Tilia americana L. var. heterophylla (Vent.) Loudon White Basswood Trillium decumbens Harb. Decumbent Trillium Trillium maculatum Raf. Mottled Trillium Trillium underwoodii Small Underwood’s Trillium Ulmus americana L. American Elm Ulmus rubra Muhl. Slippery Elm Viburnum prunifolium L. Black Haw Vitis rotundifolia Michx. Muscadine Vitis vulpina L. Frost Grape Yeatesia viridiflora (Nees) Small Yellow Bract-spike Zephyranthes atamasca (L.) Herb. Common Atamasco-lily