Guide to the Vascular Flora of the Savannas and Flatwoods of Shaken Creek Preserve and Vicinity (Pender & Onslow Counties, North Carolina, U.S.A.)

Abstract Shaken Creek Preserve (“SCP”) is a 2,448 ha (6,050 ac) natural area in Pender and Onslow Counties, North Carolina (U.S.A). Best known for its high-quality longleaf pine savanna habitat, the site contains seven savanna or savanna-like plant community types (i.e., flatwoods or sandhills), three of which are globally critically imperiled (G1): Sandy Pine Savanna (Rush Featherling subtype), Wet Loamy Pine Savanna, and Very Wet Loamy Pine Savanna. SCP hosts three Federally Endangered plant species and six Federal Species of Concern. Formerly a private hunting club, the site was virtually unknown to scientists until the 1990s; consequently, few biological inventories of SCP have been conducted. In particular, no systematic floristic inventories of the species-rich savannas have been undertaken, despite the fact that floristic data is critical to the effective management of any natural area. The goals of this study were to (1) inventory the vascular flora of the savannas, flatwoods, and sandhill community types on site through the collection of voucher specimens; (2) provide a comprehensive checklist of the flora based on collections and reports made from the site and from the same or similar habitats in the vicinity (i.e., within 2 miles of SCP); and (3) create an illustrated guide based on the checklist. In order to increase the usefulness of the guide, taxa not currently known from SCP but collected or reported from the same or similar habitats within two miles of SCP, are included in the guide. Eighty-three families containing 450 taxa, including thirty-two Significantly Rare and thirty-eight Watch List taxa, were collected or reported from SCP; an additional seven families containing a total of 102 taxa, including eighteen Significantly Rare and seven Watch List taxa, were collected or reported from the vicinity. In total, ninety families containing 552 taxa, including fifty Significantly Rare and forty-five Watch List taxa, are treated in the guide. Dichotomous keys are provided to all vouchered or reported families, genera, and species. The following features are provided for all species and infraspecific taxa: flowering and fruiting phenology; synonymy with Manual of the Vascular Flora of the Carolinas, the Flora of North America, and Flora of the Southern and Mid-Atlantic States; relevant voucher information; and, for most taxa, line drawings and/or photographs. For taxa collected from SCP, community types in which the taxa occur and estimates of abundance on site are also provided.


Introduction
Shaken Creek Preserve ("SCP") contains among the highest-quality savanna and flatwoods habitats known throughout the range of longleaf pine (Pinus palustris Mill.) ecosystems (LeBlond 2000). The 2,448 ha (6,050 ac) site is located in northeastern Pender County, North Carolina, with a small portion extending into adjacent Onslow County. Formerly a private hunting club, SCP was purchased by The Nature Conservancy in 2007. Previous botanical studies on site consisted of inventory work by LeBlond (2000) and plot studies by the Carolina Vegetation Survey (Peet et al. 2004). However, neither of these studies involved systematic surveying over multiple growing seasons, and neither included significant collecting efforts. Moreover, some savannas and flatwoods on site were not inventoried by either study. The goals of this study were to (1) inventory the vascular flora of the savanna, flatwoods, and sandhill community types on site through the collection of voucher specimens; (2) provide a comprehensive checklist of the flora based on collections and reports made from the site and from the same or similar habitats in the vicinity (i.e., within 2 miles of SCP, including all tracts comprising Sandy Run Savannas State Natural Area); and (3) create an illustrated guide based on the checklist.

Setting
SCP is a 2,448 ha (6,050 ac) tract located between 34.566°and 34.611°N and 77. 614°a nd 77.720°W in northeastern Pender County, North Carolina, with a small portion extending approximately 0.3 km into Onslow County (Fig. 1). The geographic center of the site is approximately 8.3 km south-southeast of Maple Hill, NC and 21 km northwest of the nearest point in the Atlantic Ocean. The site lies in the outer Coastal Plain ecophysiographic province and within the Cape Fear Arch geological uplift, a region extending from southeastern North Carolina into northeastern South Carolina that is characterized by unusual outcroppings of Cretaceous deposits. This area supports a suite of at least forty-four endemic or near-endemic plant taxa, many of which are rare (LeBlond 2001).
A small portion of SCP extends to the south of Shaken Creek, which otherwise forms the southern boundary of the property. The northeastern boundary follows Shelter Swamp Creek, while Flo Road west of its intersection with Williams Road forms the northwestern boundary (Fig. 2). With a small exception in the extreme northwest corner of the property, Long Ridge Road outlines the western property boundary. The irregular eastern boundary does not consistently follow any natural features or landmark. SCP is bordered to the southwest by Holly Shelter Gameland; to the northeast by Haw's Run Mitigation Site, a future component of Sandy Run Savannas State Natural Area; and in other directions by private land. Primary access is south along Williams Road from NC Highway 50, though the site is not openly accessible to the public. Sandy Run Savannas State Natural Area ("Sandy Run") is a 1,214 ha (3,000 ac) site north of SCP (Fig. 1). It is comprised of seven tracts, six of which are currently owned by the NC Division of Parks and Recreation. One tract, Haw's Run Mitigation Site, which abuts the northeastern portion of SCP, is currently owned by the NC Department of Transportation; however, transfer of this parcel to the NC Division of Parks and Recreation is impending. The various tracts comprising Sandy Run have experienced different management and land use histories, creating an array of habitats including several high-quality savannas and flatwoods. The flora of Sandy Run was recently inventoried by Taggart (2010). Though some portions of Sandy Run are slightly farther than two miles from SCP, vouchers or reports from all Sandy Run tracts were included in this work.
Holly Shelter Game Land is a 26,200 ha (64,742 ac) property south of SCP (Fig. 1). It is owned by the NC Wildlife Resources Commission, which manages the land for public outdoor recreation, particularly hunting and fishing. Only the northeast portion of the property lies within two miles of SCP; as such, plant vouchers or reports from other areas of Holly Shelter are not included in this work.

History and Land Use
Prior to its purchase by The Nature Conservancy, the land comprising SCP was owned mostly by members of the Wallace Deer Club, a private hunting group established in the 1920s. The site was virtually unknown to scientists until 1997, when William Blanchard, a member of the Wallace Deer Club and part owner of the land, introduced it to Hervey McIver, a land manager and project coordinator with The Nature Conservancy. With permission from Blanchard, McIver and Richard LeBlond, then a botanist with the NC Natural Heritage Program, undertook the first preliminary surveys of the area and realized quickly that the site contained exceptionally high-quality savannas and numerous rare species. At the time, McIver was working with Blanchard to complete a deed to The Nature Conservancy for fifty acres Blanchard owned in the nearby Neck Savanna, now a tract within Sandy Run Savannas State Natural Area. Blanchard suggested that the land now comprising SCP should also be permanently conserved and eventually agreed to sell his shares of the property. However, purchasing SCP required not just the approval of Blanchard, but of all the approximately fifty landowners who inherited or purchased property rights to the site. After three years of negotiations, The Nature Conservancy closed on the property in 2007. Members of the Wallace Deer Club retained hunting rights to the property, but the site is now owned and managed by The Nature Conservancy.
The excellent quality of many of the savannas on site, as evidenced by the abundance of rare species, the high species richness, and the absence of invasive species, can be directly attributed to the Wallace Deer Club, whose members frequently burned particular areas in order to maintain both the hunting quality and the aesthetic of the land. Evidence of disturbances other than fire in the savannas and flatwoods on site is limited to a few ditches and occasional "borrow pits," relatively small holes dug to "borrow" the soil in order to regrade and maintain the dirt roads on the property. Based on the size of the canopy trees, many savannas and flatwoods appear to have been logged as recently as the 1980s, though few or no effects on the ground layer are apparent today. Overall, the habitat quality of the site (especially those areas historically burned by members of the hunting club) remains excellent (LeBlond 2000).

Climate
The climate at SCP is warm, temperate, and humid for much of the year. The nearest weather station is approximately 29 km away in Jacksonville (Onslow County: 34. 7°N, 77.383°W) at 4.9 m above sea level. Over the thirty-year period from 1971 to 2000, the average annual temperature was 17.1°C, with a mean annual precipitation of 1,397 mm. Average daily maximum temperature was 23.1°C, and average daily minimum temperature was 11°C (State Climate Office of NC, http://www.nc-climate.ncsu.edu/; Fig.  3a). The next closest weather station is approximately 35 km away in Willard (Pender County: 34.661°N,78.046°W) at 16.7 m above sea level. Over the thirty-year period from 1971 to 2000, the average annual temperature was 17.7°C, with a mean annual precipitation of 1,377 mm. Average daily maximum temperature was 24.2°C, and average daily minimum temperature was 11.1°C (State Climate Office of NC, http://www.ncclimate.ncsu.edu/; Fig. 3b). For both stations, monthly average temperatures were highest in July and August and lowest in January and February. Monthly precipitation amounts were highest in July and August for both stations and lowest in April and October in Jacksonville and April and November in Willard.
The annual growing season, defined as the number of days in five years out of ten during which the daily minimum temperatures exceed 28°F (-2.2°C), is 235 days in Pender County and 210 days in Onslow County (Barnhill 1990, Barnhill 1992. Elevation at SCP ranges from 4 m (13 ft) to 12.9 m (42 ft) above sea level (NC Department of Transportation, http://www.ncdot.gov/it/gis/default.html).

Soils
Twelve soil types representing five soil orders are mapped at SCP (Barnhill 1990, Barnhill 1992Fig. 4). Ultisols are the most abundant in type, though Spodosols are the most abundant in area. Entisols comprise 21.4% of the total area and are the dominant soil order along Shaken Creek and Shelter Swamp Creek. While most areas mapped as Entisols support swamp communities, a few savannas do occur over Entisols, as along Alligator Lake Road and the eastern portion of Mule Pen Road. Histosols comprise 8.7% of the total area and, with one small exception, are restricted to the central western portion of the property, which is dominated by Pond Pine Woodland (Typic subtype) and High Pocosin (Typic subtype) communities (sensu Schafale 2012). No savanna or savanna-like community types are known to occur on Histosols at SCP. Inceptisols comprise 14.2% of the total area and are the dominant order in the central eastern portion of the property, an area that has not been managed with fire in many decades. Excepting one very small area on the west side of the north end of Alligator Lake Road, no savannas or savanna-like areas occur at SCP in areas mapped as Inceptisols. Spodosols comprise 36. portions of the property. Many of the most species-rich savannas, most notably those along Flo Road east of its intersection with Fill Road, occur in areas mapped as Ultisols.
A brief synopsis of each of the twelve soil types, arranged by soil order, is provided below.

Entisols
Muckalee (Mk) loam, frequently flooded (Coarse-loamy, siliceous, superactive, non-acid, thermic Typic Fluvaquents) Poorly-drained soils on floodplains. Slopes are 0-2%. Typical soil texture is loam in the upper 30 cm and sandy loam with thin strata of loamy sand or sand from 30 cm to 150 cm. These soils have a seasonal high water table between 15 cm and 46 cm below the soil surface and are frequently flooded for brief periods (Barnhill 1990). This is the primary mapping unit along Shaken Creek and Shelter Swamp Creek and is occupied predominantly by Blackwater Bottomland Hardwoods (High subtype) and other swamp communities.
Pactolus (PaA) fine sand (Thermic, coated Aquic Quartzipsamments) Moderately well-drained or somewhat poorly-drained soils in slight depressions in uplands and on low ridges on terraces. Slopes are 0-2%. Typical soil texture is fine sand to 200 cm below the soil surface. These soils have a seasonal high water table between 46 cm and 76 cm below the soil surface and are not subject to flooding (Barnhill 1990). This mapping  Barnhill (1990Barnhill ( , 1992 Very poorly-drained soils on interstream divides. Slopes are 0-2%. Typical soil texture is muck in the upper 89 cm, fine sandy loam between 89 cm and 114 cm, sandy clay loam between 114 cm and 191 cm, and fine sandy loam between 191 cm and 200 cm. These soils have a seasonal high water table at or near the soil surface for about six months and are rarely flooded for brief periods (Barnhill 1990). This mapping unit is nearly restricted to the central-western portion of the property and supports Pond Pine Woodland (Typic subtype) and High Pocosin (Typic subtype) communities.

Inceptisols
Torhunta (To) mucky fine sandy loam (Coarse-loamy, siliceous, active, acid, thermic Typic Humaquepts) Very poorly-drained soils on interstream areas and on stream terraces. Slopes are 0-2%. Typical soil texture is mucky fine sandy loam in the upper 8 cm, fine sandy loam between 8 cm and 152 cm, and sandy loam and sand to 200 cm. These soils have a seasonal high water table between 15 cm and 46 cm below the soil surface and are rarely flooded for brief periods (Barnhill 1990). This mapping unit occupies the central-eastern portion of the property, a fire-suppressed area that supports few or no savanna, flatwood, or sandhill communities.

Spodosols
Leon (LnA) fine sand (Sandy, siliceous, thermic Aeric Alaquods) Poorly-drained soils on interstream areas. Slopes are 0-2%. Typical soil texture is fine sand to 200 cm below the soil surface. These soils have a seasonal high water table less than 30 cm below the soil surface and are not subject to flooding (Barnhill 1990). This is the primary mapping unit of the central portion of the property and is well-represented along Half Moon Road and the portion of Flo Road between the powerline cut and Meadow Lake Road. The best and most accessible examples of Wet Pine Flatwoods (Typic subtype), Sandy Pine Savanna (Typic subtype), and Sandy Pine Savanna (Rush featherling subtype) are found in areas mapped as Leon fine sand.

Mandarin (Ma) fine sand (Sandy, siliceous, thermic Oxyaquic Alorthods)
Somewhat poorly-drained soils on moderately elevated areas in interstream divides. Slopes are 0-2%. Typical soil texture is fine sand in the upper 101 cm and sand between 101 cm and 200 cm. These soils have a seasonal high water table between 46 cm and 107 cm below the soil surface and are not subject to flooding (Barnhill 1990). This mapping unit is restricted to narrow ridges in the central and western portions of the property. The largest example is in the northwest corner of the property south of Long Ridge Road, which supports extensive Wet Pine Flatwoods (Typic subtype) and Sandy Pine Savanna (Typic subtype) communities.

Murville (Mu) muck (Sandy, siliceous, thermic Umbric Endoaquods)
Very poorly-drained soils on interstream areas and in depressions. Slopes are 0-2%. Typical soil texture is muck in the upper 8 cm, mucky fine sand between 8 cm and 28 cm, fine sand between 28 cm and 124 cm, loamy fine sand between 124 cm and 140 cm, and fine sand between 140 cm and 200 cm. These soils have a seasonal high water table less than 30 cm below the soil surface and are not subject to flooding (Barnhill 1990). This mapping unit is the largest in area at SCP and dominates the west-central and western portions of the property. It is particularly abundant north of Mule Pen Road and along the portion of Indian Grave Road east of the powerline cut. Most areas mapped as Murville support Pond Pine Woodland (Typic subtype) communities.

Ultisols
Baymeade (BaB) fine sand (Loamy, siliceous, semiactive, thermic Arenic Hapludults) Well-drained soils on low ridges and convex slopes in uplands. Slopes are 1-4%. Typical soil texture is fine sand in the upper 64 cm, fine sandy loam between 64 cm and 148 cm, and fine sand between 148 cm and 200 cm. These soils have a seasonal high water table between 122 cm and 152 cm below the soil surface and are not subject to flooding (Barnhill 1990). The smallest mapping unit on site, Baymeade fine sand is restricted to one area north of Mule Pen Road, approximately 1 km west of the intersection of Mule Pen Road and Williams Road. This small area is among the driest and "hilliest" at SCP and supports a Pine/Scrub Oak Sandhill (Mesic Transition subtype) community.
Foreston (Fo) loamy fine sand (Coarse-loamy, siliceous, semiactive, thermic Aquic Paleudults) Moderately well-drained soils on slightly convex interstream divides near shallow drainageways. Slopes are 0-2%. Typical soil texture is loamy fine sand in the upper 33 cm, fine sandy loam between 33 cm and 102 cm, fine sandy loam with pockets of loamy fine sand between 102 cm and 140 cm, fine sandy loam with strata of loamy sand between 140 cm and 168 cm, and sandy clay loam with strata of sand and sandy loam between 168 cm and 200 cm. These soils have a seasonal high water table between 76 cm and 107 cm below the soil surface and are not subject to flooding (Barnhill 1990). Scattered throughout the property, this mapping unit is perhaps best represented along Flo Road near its intersection with Fill Road, an area that supports high-quality Wet Loamy Pine Savanna communities and, in depressional areas, Very Wet Loamy Pine Savanna communities.
Pantego (Pn) mucky fine sandy loam (Fine-loamy, siliceous, semiactive, thermic Umbric Paleaquults) Very poorly-drained soils on interstream areas. Slopes are 0-2%. Typical soil texture is mucky fine sandy loam in the upper 25 cm, fine sandy loam between 25 cm and 61 cm, sandy clay loam between 61 cm and 150 cm, clay loam with strata of sandy clay loam between 150 cm and 183 cm, and sandy clay loam with thin strata of loamy sand between 183 cm and 200 cm. These soils have a seasonal high water table within 46 cm of the soil surface and are rarely flooded for brief periods (Barnhill 1990). This mapping unit is restricted to a small area in the extreme east-central portion of the property. No savannas, flatwoods, or sandhills are known from this area.
Stallings (St) loamy fine sand (Coarse-loamy, siliceous, semiactive, thermic Aeric Paleaquults) Somewhat poorly-drained soils on interstream areas and in shallow depressions on convex divides. Slopes are 0-2%. Typical soil texture is loamy fine sand in the upper 30 cm, fine sandy loam between 30 cm and 114 cm, fine sandy loam with pockets of sandy clay loam between 114 cm and 168 cm, and sandy clay loam with thin layers of fine sandy loam between 168 cm and 200 cm. These soils have a seasonal high water table between 46 cm and 76 cm below the soil surface and are not subject to flooding (Barnhill 1992). As with the preceding map unit, Stallings loamy fine sand is restricted to a small area in the extreme east-central portion of the property. No savannas, flatwoods, or sandhills are known from this area.
Woodington (Wo) fine sandy loam (Coarse-loamy, siliceous, semiactive, thermic Typic Paleaquults) Poorly-drained soils on interstream areas and in depressions near drainageways. Slopes are 0-2%. Typical soil texture is fine sandy loam in the upper 43 cm and fine sandy loam with pockets or strata of loamy fine sand between 43 cm and 200 cm. These soils have a seasonal high water table between 15 cm and 30 cm below the soil surface and are not generally subject to flooding, though low areas may be subject to ponding for brief periods (Barnhill 1990). This mapping unit occurs commonly in the northeastern and southeastern portions of the property, particularly along Bug Ridge Road, at the graded end of Half Moon Road, and along the far eastern portion of Flo Road. Scattered and usually small examples of savannas, flatwoods, and sandhills occur in areas mapped as Woodington fine sandy loam.

Plant Community Types
Seven savanna, flatwoods, or sandhill plant community types were distinguished at SCP following Schafale (2012) ( Table 1). Among these community types, three are globally critically imperiled (G1); the remainder are globally imperiled or vulnerable (G2G3). In general, the drier savanna or savanna-like community types (i.e., Pine/Scrub Oak Sandhill (Mesic Transition subtype) and Mesic Pine Savanna (Coastal Plain subtype)) are restricted to slightly-elevated ridges that occur mostly in the central and western portions of the property; other areas on site are typically dominated by wetter community types (i.e., Wet Pine Flatwoods (Typic subtype) or one of the four Wet Pine Savanna community types; Fig. 5).

Plant community types in Shaken
Creek Preserve included in this work. Community types and their associated ranks follow Schafale (2012). Community types are presented in order of increasing soil moisture -i.e., from driest community type (Pine/Scrub Oak Sandhill (Mesic Transition Subtype)) to wettest (Very Wet Loamy Pine Savanna). S1 = Critically Imperiled, 1-5 occurrences in state; S2 = Imperiled, 6-20 occurrences in state; S3 = Vulnerable, 21-100 occurrences in state; G1 = Critically Imperiled, 1-5 occurrences in world; G2 = Imperiled, 6-20 occurrences in world; G3 = Vulnerable, 21-100 occurrences in world As is true of most longleaf pine-dominated communities, all the community types treated herein are dependent on frequent, low-intensity fires to maintain their integrity (Figs 6,7). Variations in fire intensity based on vegetation type.
a: In savannas that are frequently burned and lack significant woody vegetation, fires are small enough to be stepped over harmlessly (photo by R. Thornhill). b: Fire intensity increases along the woody margins of savannas and flatwoods (photo by R. Thornhill).

Figure 7.
Fire time-series in a Wet Loamy Pine Savanna community type. Many savanna species, particularly bunchgrasses, flower only following growing-season fires. This sequence of photos shows the effects of fire on the flowering of Ctenium aromaticum (toothache grass).
a: April 30, two days after a burn (photo by R. Thornhill). b: June 27, just less than two months after a burn. Notice the profusion of flowering stalks of Ctenium aromaticum in the burned area (left) versus their near-absence in the unburned (right) area (photo by R. Thornhill).
property, and Pond Pine Woodland (Typic subtype and Canebrake subtype) along portions of Williams Road and Half Moon Road (Fig. 8).
In the following discussion community types are presented in order from driest to wettest (i.e., according to increasing soil moisture). For each community type the most similar NatureServe association (see http://www.natureserve.org/explorer) is provided in brackets. Two community types not formally treated in this thesis: Pocosin and Pond Pine Woodland. The overall species composition of these community types is very similar to (albeit less rich) than the flatwoods and savanna community types formally treated in this work. Indeed, virtually all species in pocosins and pond pine woodlands are also found in flatwoods and/or savannas; consequently, this guide will facilitate the identification of species in pocosins and pond pine woodlands as well as in flatwoods and savannas.

Pine/Scrub
The canopy consists of Pinus palustris and Pinus serotina Michx., with occasional Pinus taeda L. In addition to those species listed for the preceding community types, the sometimes-dense shrub layer also contains species characteristic of wetter soils, such as The use of the terms "flatwoods" and "savannas" is notoriously variable, and sometimes contradictory, from person to person. In general "flatwoods" has been used to designate savanna-like areas that are shrubbier and/or less floristically diverse than true savannas. This work follows Schafale (2012) in distinguishing flatwoods by their floristic composition and lower small-scale species richness. While Wet Pine Flatwoods (Typic subtype) may have a naturally denser shrub layer than savannas, essentially all the community types treated in this work become shrubby in the absence of fire; relative shrub dominance is, therefore, a poor indicator of community type. Wet Pine Flatwoods (Typic subtype) often grades into Sandy Pine Savanna (Typic subtype), particularly on Spodosol soils. In these cases Wet Pine Flatwoods (Typic subtype) can be distinguished by the abundance of Pyxidanthera barbulata, Pteridium aquilinum var. pseudocaudatum, and Vaccinium crassifolium; the absence or near-absence of bunchgrass species characteristic of wetter sites, particularly Ctenium aromaticum and Muhlenbergia expansa; the absence of carnivorous species (with the exception of species of Drosera L.); and an overall lower small-scale species richness. In fire-suppressed areas, it is often difficult to determine whether the natural community type is Wet Pine Flatwoods (Typic subtype) or one of the a b Figure 9.
Wet Pine Flatwoods (Typic subtype) a: A typical wet pine flatwoods (photo by R. Thornhill). b: When frequently burned, the physiognomy of wet pine flatwoods resembles that of Pine Savannas; however, species diversity and overall richness, especially at a small scale, is lower in in this community type than in true savannas (photo by R. Thornhill).
dominance of Pleea tenuifolia. The environmental factors responsible for this community type are unclear. At SCP both the Rush Featherling and Typic subtypes occur on Leon soils and in close proximity to one another. However, the author has noticed that Pleea tenuifolia is sometimes abundant in local depressions within the Typic subtype, an observation that suggests that P. tenuifolia possibly favors wetter soils. Perhaps, then, the Rush featherling subtype has a somewhat higher water table than the Typic subtype, though this hypothesis has not been tested.  have been collected in thickets along the roadside edge of Wet Loamy Pine Savannas. The herbaceous layer is very diverse and generally includes all taxa present in the Sandy Pine Savanna communities plus many other taxa. Among bunchgrasses, Ctenium aromaticum, Muhlenbergia expansa, and Sporobolus pinetorum dominate or co-dominate with Aristida stricta. Herbs that are often present in Wet Loamy Pine Savannas but not in Sandy Pine Savannas include Chaptalia tomentosa, Cirsium virginianum, Eryngium L. spp., Lysimachia loomisii, Polygala hookeri, P. ramosa, and many Rhynchospora spp.

Wet Loamy
As their names imply, both Loamy Pine Savanna community types are distinguished from Sandy Pine Savanna community types by somewhat finer-textured soils. In general, finertextured soils are more fertile than and have a higher water-holding capacity than coarsertextured soils-conditions that would seem to be favorable to the growth of most plant species. These environmental factors may explain, at least partially, the exceptionally high species Canopy species include those of other Wet Pine Savannas, though Pinus palustris is often less abundant. Taxodium ascendens, not usually found in the other communities, also frequently occurs. Shrub species that are more common in this community type than in others include Morella cerifera (L.) Small and Ilex myrtifolia Walter. Vines are generally uncommon, though Mikania scandens (L.) Willd. and Toxicodendron radicans (L.) Kuntze var. radicans are more likely to be found in this community type, particularly along swampy margins or in unburned sites, than in other community types. The herbaceous layer may include all taxa present in other Wet Pine Savannas plus an additional suite of rare species: Allium species 1, Carex lutea, and Thalictrum cooleyi, all of which are strong indicators for this community type. Aristida stricta is often scarce or even entirely absent, replaced by other bunchgrass species, particularly Muhlenbergia expansa. Many wetland herbs that are sometimes found in Wet Loamy Pine Savannas are often much more abundant in Very Wet Loamy Pine Savannas. Examples inlcude Carex striata Michx., Chaptalia tomentosa, and Eryngium spp. Boggy species, like Eriocaulon decangulare var. decangulare and Lachnocaulon anceps, which are restricted to borrow pits and depressions in other community types, are also more likely to occur in the savannas proper of this community type.
Globally, Very Wet Loamy Pine Savannas have a small, patchy distribution, and the environmental factors responsible for their occurrence are unclear. As noted by Schafale (2012), the abundance of wetland species would seem to indicate a wetter soil than that of Wet Loamy Pine Savannas. In most cases, however, Wet Loamy Pine Savannas grade directly into swamps or pocosins on their wet edges; why in rare cases Very Wet Loamy Pine Savannas form in these ecotonal positions is uncertain. The natural fire frequency of Very Wet Loamy Pine Savannas is also unclear but may be somewhat lower than that of the other savanna communities due to a higher water table and a suspected slightly higher natural shrub density. Some Very Wet Loamy Pine Savannas exhibit localized inclusions of calcium (in the form of marl) that increase soil pH in small areas (Schafale 2012). Rare in the Coastal Plain of NC, these inclusions were once thought to explain the curious distribution of this community type; however, many calcium deposits underlying Very Wet Loamy Pine Savannas appear to be several feet below the soil surface, where they would presumably exert little impact on the pH of the upper portion of the soil in which most plants root. Moreover, one study (Taggart 2012) suggested that even in Very Wet Loamy Pine Savannas in which inclusions of high pH have been reported, most of the soil throughout the savanna is still strongly acidic. Further research into the environmental factors associated with this community type is certainly warranted.

Preliminary Species List
A preliminary list of plant taxa reported from SCP by LeBlond (2000) and by the Carolina Vegetation Survey (Peet et al. 2004) was compiled. Taxa collected or reported from various tracts comprising Sandy Run Savannas State Natural Area were also included; for these taxa, the following sources were referenced: LeBlond and Weakley (1991), LeBlond (1999), LeBlond (2000), Taggart (2010 Table 2. List of rare taxa (i.e., "Significantly Rare" or rarer sensu Gadd and Finnegan 2012) collected or reported from savannas, flatwoods, or sandhills in Shaken Creek Preserve or the vicinity (i.e., within a 2-mile radius of Shaken Creek Preserve, including Sandy Run Savannas State Natural Area). Status and rank designations follow Gadd and Finnegan (2012). Parentheses around a taxon indicate that the taxon is not known from Shaken Creek Preserve but is known from the vicinity. Taxa for which voucher specimens have been collected (by the senior author or others) are indicated with a "yes" in the second column. The taxonomy followed in this work and that of Gadd and Finnegan (2012) differ in the following instances: 1) Gadd and Finnegan (2012)  • Distribution: The distribution of taxa is provided by listing the community types in which the taxa have been collected or reported within the study area. For taxa collected or reported from SCP, the community types (sensu Schafale 2012) in which the taxa occur on site are listed from driest to wettest (i.e., in order of increasing soil moisture) and are abbreviated as follows (see Table 1 Taggart (2010) or reported from the vicinity by LeBlond (1999) or LeBlond (2000), community types as provided by those authors are given. For all other taxa (i.e., those taxa collected or reported from the vicinity by sources other than the afoermentioned), habitat according to Weakley (2012) is provided in lieu of community types. • Notes: Within each "notes" section, several bits of information are provided in the following order: 1) an estimate of abundance adadpted from Palmer et al. (1995) (see Table 4) for taxa collected by the senior author in SCP; 2) flowering and fruiting phenology from Weakley (2012) and supplemented, in some cases, with personal observation; 3) voucher information from specimens deposited in the following herbaria: DUKE, NCSC, NCU, and WNC. Within a list of vouchers, specimens collected in SCP are listed first, followed by specimens collected from the vicinity, which are arranged alphabetically by site name, then by tract name (if within Sandy Run), and finally by collector last name. For taxa of conservation concern that were collected in Sandy Run, the name of the tract in which the voucher was collected is purposefully omitted; and 4) in brackets, synonymy with , the Flora of North America Project, and Weakley (2012).   Gadd and Finnegan (2012) with the exception of Paspalum praecox, which lacks varietal recognition in Gadd and Finnegan (2012) but which is here treated as comprising two varieties, for which the status and ranks are simply the same as those given by Gadd and Finnegan (2012) for the species. Parentheses around a taxon indicate that the taxon is not known from Shaken Creek Preserve but is known from the vicinity. Taxa for which voucher specimens have been collected (by the senior author or others) are indicated with a "Y" in the second column.

Density Description
Abundant Dominant or co-dominant in one or more common communities Frequent Numerous in one or more common communities but not dominant in any common community Occasional Widely scattered in several communities, including one or more common communities Infrequent Few individuals or colonies but found in several locations or communities Rare Few individuals or colonies limited to one or very few locations or communities Six taxa included in this guide bear numeric "placeholder" epithets, as currently listed in Weakley (2012). Of these six taxa, the following four are presumed to be new to science: Allium species 1, Coreopsis species 1, Scleria species 1, and Xyris species 1. The remaining two taxa-Dichanthelium species 3 and D. species 12-were recognized by previous authors (see synonymy for those taxa in the checklist); however, the appropriate combination has yet to be made within Dichanthelium.Based on field observations by the senior author, instances of known hybridization appear to be rare in the flora. (Actual Table 4. Descriptions for estimating abundance of taxa collected by the senior author in Shaken Creek Preserve (adapted from Palmer et al. 1995).
hybridization events may be more common but are beyond the scope of this research.) One notable exception, however, is Sarracenia × catesabaei Elliott (= S. flava L. × S. purpurea L.). (See the key to Sarracenia for a discussion of hybridization within that genus.) Hybrids are nottreated as separate taxa in this guide.

Identification Keys
Dichotomous keys were created to all taxa collected or reported from savannas, flatwoods, or sandhill community types in SCP and the vicinity (i.e., in areas within two miles of SCP, including all tracts within Sandy Run Savannas State Natural Area). The order of the keys follows that of the checklist (i.e., a key is first provided to four main vascular plant groups, then within each of these groups, keys proceed alphabetically by family and then genus). In addition, three "auxiliary keys" are provided: a vegetative key to common savanna bunchgrasses (following the key to genera of Poaceae); a key to herbaceous eudicotyledonous taxa with simple, opposite, more-or-less ovate leaves (following the key to families of basal angiosperms, magnoliids, and eudicotyledons); and a vegetative key to frequently confused ericaceous subshrubs (following the key to genera of Ericaceae). Keys were adapted from , the cited Flora of North America treatments, Weakley (2012), and personal notes. In the keys exceptional values for numeric character ranges are indicated in parentheses (e.g., leaf blade 1-2(-4) cm wide). Definitions, explanatory notes, and exceptional non-numeric character states are also placed in parentheses (e.g., corolla pink (rarely white)).
During herbarium searches, vouchers of taxa collected by others in SCP or in the vicinity but not collected by the senior author in SCP were carefully examined. In five cases the senior author disagreed with the determinations of such vouchers. Nevertheless, since the original determinations were always of taxa whose habitat and distribution make them plausible components of the flora, these taxa were included in the keys, where indicated by a plus (+) symbol. These taxa are not, however, formally treated in this work (i.e., they do not appear in the checklist) and are not included in summary statistics. Additionally, fortyfour taxa that are not known from the habitats treated in this work but that often occur in roadsides or other disturbed areas immediately adjacent to such habitats, are also included in the keys, where indicated by a double-dagger ( ‡) symbol. These taxa, too, are neither formally treated in this work nor included in the summary statistics. Finally, though only one exotic taxon is reported in this work, several of the forty-four aforementioned taxa (those strictly of roadsides or disturbed areas) are exotic (i.e., not native to the Coastal Plain of North Carolina, sensu Weakley 2012). Exotic taxa are indicated in the keys with an asterisk (*).

Data resources
Dichotomous keys were adapted from , the cited Flora of North America treatments, Weakley (2012), and personal notes. Taxonomic concepts and nomenclature usually follow Weakley (2012) but in some cases follow the cited Flora of North America treatments. Status and ranks for taxa of conservation concern (i.e., those taxa listed by Gadd and Finnegan 2012) were adopted from Gadd and Finnegan (2012); see Tables 2, 3). Plant community types were identified using Schafale (2012). Line drawings were obtained from the following public domain works: Britton andBrown (1913), Hitchcock (1950), United States Department of Agriculture, Natural Resources Conservation Service (2012). All photographs, with the exception of those for Carya tomentosa, were taken by Robert Thornhill.
Notes: Mid Jun-Aug; Aug-Oct. The specimen for this report (Thornhill 1547, NCSC), which was collected by the author at the edge of a dirt road and powerline savanna in Shaken Creek Preserve, has calyx lobes somewhat shorter and leaves somewhat narrower than is typical for P. setosum. However, based on comparisons to specimens at NCSC and NCU and following the advice of better botanists (in particular, Derrick Poindexter (NCU)), the specimen seems at least to align most closely with P. setosum.
More study is needed to clarify the taxonomy of this genus. P. setosum is also reported within a 2-mile radius of Shaken Creek Preserve by the North Carolina Natural Heritage Program (http://www.ncnhp.org) (EO status "current," accuracy "medium"), though no vouchers for this report have been seen by the senior author.         (2012). Note: Understanding some basic terminology is critical to the successful use of the following keys to Pteridophytes families, genera, and species. Pinnate indicates lobing (usually of leaves or leaf segments) entirely to the midrib, whereas pinnatifid indicates lobing to near the midrib. Pinnatepinnatifid refers to a leaf that is once-pinnate and whose segments (pinnae) are themselves pinnatifid. The spore-producing structures of many ferns are borne in masses called sori, which may be either exposed or covered by the margin of the leaves (a false indusium) or a separate structure (a true indusium). Leaf-like structures that bear sporangia are called sporophylls; these may be similar to the sterile leaves or may be highly modified (e.g., the compacted, cone-like structures, or strobili, of Lycopodiaceae).  [Blechnaceae] Woodwardia Sm.
Key adapted from Watson (1993), Weakley (2012). Note: Taxodium distichum (L.) Rich. has not been found in savannas or flatwoods on site, though it has been seen in swamps. Nevertheless, it is included in the key below (where indicated by a double-dagger symbol, ‡) to facilitate the distinguishing of it from T. ascendens Brongn., an occasional component of the wettest savannas. In the following key leaf and branchlet characters of T. ascendens refer to mature trees; foliage of juvenile trees often mimics that of T. distichum.
Leaf and branchlet characters of T. distichum refer to both mature and juvenile trees; however, in the crowns of mature T. distichum, leaf and branchlet characters sometimes mimic those of T. ascendens. For these reasons, accurate identification of the two species often requires observation of other, non-foliage features, including the stature of the "knees," the thickness and texture of the bark, and the habitat in which the plant grows. Fig. 22 1 Leaves mostly vertically ascending, appressed and overlapping, spirally arranged; branchlets ascending from twigs, secundly erect; bark 1-2.5 cm thick, furrowed, dark-brown, not exfoliating; larger knees short, rarely > 4 dm tall, with thick, compact bark on top; trees of isolated depressions, wet savannas, pocosins, other wet peaty habitats, and, less commonly, blackwater swamps T.
Key adapted from , Kral (1993), and Weakley (2012).              (2010), only one, Cyperus haspan L., was reported from pine savannas or flatwoods. Nevertheless, a few Cyperus species could be found in savannas or flatwoods, and the following key attempts to accommodate such discovery. Included in the key below are those species seen by the senior author growing in disturbed areas near savannas or flatwoods in Shaken Creek Preserve and also those species reported by Taggart (2010) as growing in disturbed areas but whose habitat description in Weakley (2012)       [Eriocaulaceae] Eriocaulon L.
Key adapted from Kral (2000a), Weakley (2012). Fig. 48a (2010); however, the voucher for this report (Taggart SARU 217, WNC) appears, based on the pubescent scapes and gradually tapering leaf tips, to be Lachnocaulon anceps (Walter) Morong. Though not otherwise reported for or collected in Shaken Creek Preserve or the vicinity, L. beyrichianum may occur in the area and is therefore maintained in the key below, where indicated by a plus (+) symbol. [Hypoxidaceae] Hypoxis L. (2002) (2002), Weakley (2012). NOTE: The inflorescence of Sisyrinchium is comprised of 1-11(-15), usually pedicellate flowers (and their tiny, hyaline bracteoles) that emerge from within two green or purplish-tinged "spathes." Inflorescences and associated spathes occur singly at the tips of branch-like peduncles in most species but are characteristically paired at the stem apex in S. albidum and S. capillare. In these latter two species, one of the two inflorescences is often concealed by a large, erect, leaf-bract, which may give the false impression that only one inflorescence is present. Several unusual Sisyrinchium specimens were collected in Sandy Run [Neck] by Wilbur, who determined the specimens to be S. arenicola, a taxon listed by Weakley (2012) as occurring from MD northward. The specimens have the following features, all of which agree with S. arenicola: stems 2.7-3.4 mm wide, leaf bases persistent in fibrous tufts, outer spathe bracts 12-21 mm long, and capsules 3.2-4.1 mm long. Pending further review, these specimens are here treated as S. arenicola, despite the geographic anomaly. Sisyrinchium rosulatum E.P. Bicknell has not been found in pertinent habitats in Shaken Creek Preserve or the vicinity; however, the species has been collected along roadsides very near savannas and flatwoods and is, for convenience, included in the key below, where indicated by a double dagger symbol ( ‡). Fig. 52a     [Nartheciaceae] Aletris L.

Calamovilfa brevipilis (from Britton and Brown 1913).
Guide to the Vascular Flora of the Savannas and Flatwoods of Shaken Creek ...

Vegetative Key To Common Savanna Bunchgrasses
Key adapted from notes provided by Richard LeBlond and from Weakley (2012).    [Poaceae] Andropogon L.

Key adapted primarily from Weakley (2012), with supplemental information from Campbell (2003).
Note: The complex inflorescences of Andropogon necessitate the use of specialized terminology in botanical keys. In Andropogon (and Schizachyrium) paired spikelets create V-shaped dispersal units consisting of the following parts: the sessile spikelet at base; the pedicellate spikelet (usually vestigial or absent) at the summit of the pedicel, which forms one arm of the "V"; and the rachis internode (lacking a spikelet at summit), which forms the other arm of the "V." (In the key below, spikelet measurements do not include lengths of awns, when present.) Several V-shaped dispersal units are aggregated one on top of the other to create a raceme (or "rame"). Several racemes are digitately aggregated at the apex of a peduncle and enclosed at least partially by a leaf-like raceme sheath. The racemes, peduncle, and subtending raceme sheath collectively form the inflorescence unit.

A. capillipes+
Guide to the Vascular Flora of the Savannas and Flatwoods of Shaken Creek ...  [Poaceae] Aristida L.
Key adapted from Allred (2003), Weakley (2012).   (2012), are warranted regarding the key below. First, spikelet measurements refer only to mature spikelets, recognizable by their firm, plump, usually whitish fertile lemmas; immature spikelets are typically longer than mature spikelets and are not accounted for in the key. When measuring spikelet length, measure from the point of attachment of the lower glume to the apex of the highest spikelet structure (usually either the upper glume or the fertile lemma). Pubescence, an oft-used character in distinguishing Dichanthelium taxa, must also be evaluated carefully. When assessing internode pubescence, ignore the basalmost internode, which is generally shortened and uncharacteristic, and examine the first few elongated internodes. Nodes that are referred to as "bearded" have hairs that are longer, often denser, and of either a different structure or orientation than the hairs of the internodes and sheaths. Ligules are also an important diagnostic feature in Dichanthelium. When attempting to identify a specimen, examine several ligules, as the length and structure of ligules can vary within individuals.   [Poaceae] Paspalum L.
Key adapted from , Allen and Hall (2003), and Weakley (2012). Note: In disturbed areas adjacent to savannas (e.g., roadsides, powerline cuts, mowed areas), several weedy, generally exotic Paspalum taxa often co-occur with native Paspalum taxa. In order to facilitate accurate identification in such areas, these weedy taxa are included in the key below, where distinguished by a double-dagger symbol ( ‡).   [Smilacaceae] Smilax L.

Crotalaria purshii
Guide to the Vascular Flora of the Savannas and Flatwoods of Shaken Creek ...          Key adapted from . Note: Physostegia virginiana (L.) Benth. ssp. praemorsa (Shinners) P.D. Cantino was reported from Sandy Run by Taggart (2012). However, the voucher for this taxon (Taggart SARU 238,WNC!) appears to the senior author, based on the bluntly serrate leaf margins, to be Physostegia purpurea (Walter) S.F. Blake. Though not otherwise reported or collected in Shaken Creek Preserve or the vicinity, P. virginiana ssp. praemorsa may occur in the area and, in order to facilitate its distinction from P. purpurea, is maintained in the key below, where indicated by a plus (+) symbol.
Key adapted from ), Weakley (2012. Note: For assistance in distinguishing the following taxa from some similar herbs with opposite, more-or-less ovate leaves, see the auxilliary key immediately following the key to dicot families.  Fig. 230a, b, c, d, e 1 Leaf blades elliptic to obovate, mostly 1.5-4 cm wide, 2-4× as long as wide, not or only sparsely glandular-punctate on adaxial surface; mature fruits 3.0-4.5 mm in diam.

Orobanchaceae
The following taxa are all hemiparasitic on the roots of a variety of species. Key adapted from .      [Sarraceniaceae] Sarracenia L.
Key adapted from Mellichamp andCase (2009), Weakley (2012). Note: Hybridization is common among many taxa of Sarracenia. Though not included in the key below, hybrids are generally recognizable by their intermediate morphology. At Shaken Creek Preserve, Sarracenia × catesbaei Elliott (= S. flava L. × S. purpurea L.), with its erect but relatively dwarfed (compared to S. flava) stature, can usually be found in savannas where both parents cooccur (as in the savannas along Flo Road, east of Meadow Lake Road). Hybrids involving S. rubra Walter ssp. rubra, a species reported for the site by LeBlond (2000) but not seen by the senior author, are also possible, though the presumably small population size of S. rubra would likely limit extensive occurrences of such hybrids. Key adapted from Weakley (2012). Note: The leaf characters in the following key refer to mature leaves; the earliest one or two leaves in many species of Viola display atypical shapes and/or margins, which are not accounted for in the key. Fig. 247a Acknowledgements I would first like to thank my advisor, Dr. Alexander Krings, for his patience, attention to detail, and tireless dedication throughout this project, manifested perhaps most conspicuously in his willingness to comb repeatedly through the minutia of drafts of this lengthy manuscript in search of even the smallest typographical errors, of which there were (but hopefully are not now) plenty. I am also grateful to the other members of my committee: Dr. Jon Stucky, who introduced me to Shaken Creek Preserve and helped unveil to me the mysteries of graminoids, and to Dr. David Lindbo, whose humor and perspective have been a tremendous asset.  Comparison of the richest genera in the savannas, flatwoods, and sandhills in Shaken Creek Preserve ("SCP"), in the vicinity (i.e., within two mile of Shaken Creek Preserve, including Sandy Run Savannas State Natural Area; "SR+V"), and in both Shaken Creek Preserve and the vicinity ("SCP and SR+V"). "Taxa" includes species, subspecies, and varieties. Genera represented by ≥ 7 total taxa are represented individually; genera represented by < 7 total taxa are not included. Values appearing within the columns indicate the total number of taxa from each included genus. Values appearing above each column indicate the total number of taxa across all included genera; percentages appearing above each column indicate the percentage of the flora of the particular area that is represented by the included genera. Values include taxa vouchered or known only from reports. Suppl. material 4 information regarding the flora of Sandy Run Savannas State Natural Area; he also provided much-appreciated encouragement and advice throughout this project. Dr. Layne Huiet at Duke University, CarolAnn McCormick at UNC Chapel Hill, and Dr. Eric Schuettpelz at UNC Wilmington provided cheerful curatorial assistance at their respective herbaria.
Special thanks to Josh Justice, Robert Swinson, and all the members of the Wallace Deer Club, who graciously allowed me to sleep and take cold showers in their lodge. (An extraspecial thanks to that anonymous hunting club member who eventually showed me the circuit breaker for the hot-water heater.) I also thank the NC Plant Conservation Program, the NC Natural Heritage Program, and The Nature Conservancy, who enabled and supported this research in various ways. In particular, I would like to thank Hervey McIver for his enthusiastic stewardship of Shaken Creek Preserve-and for his optimistic and adventuresome spirit. Twenty years from now, I hope I, too, am crashing through overgrown savannas exclaiming of their restoration potential: "With just a few good burns…." Thank you to the past and present members of the NC State floristics group: Rachel Clark, Kelly Hines, and Amanda Saville, for paving the way; and Lee Kimmel, Casie Reed, and Jenny Stanley, for your encouragement and collective goofiness. Thank you also to the past and present office staff of the NCSU Plant Biology Department: Carol Apperson, Christine Brown, Vicki Lemaster, and, especially, Sue Vitello. Without you, I certainly would not have made it this far-and, worse, I would probably still be filling out travel authorization forms incorrectly.
I am deeply indebted to the NC Native Plant Society, the NC Academy of Science, and the US Fish and Wildlife Service for funding this project. Because of these groups, my use of "indebted" is still mostly metaphorical…mostly.
Finally, to my family: Mr. Andy and Ms. Dottie, thank you for letting me repeatedly convert your dining room into a floristics laboratory; Mom and Dad, you are amazing people and wonderful parents, as evinced by the fact that your son studies plants-and you love him anyway; Bro, let's puzzle over laurel and willow oaks again soon; and Audrey, my sweet wife, who may never get to enjoy a walk through the woods with an undistracted husband, thank you for your patience and love.

Author contributions
Robert Thornhill conducted field research and wrote the manuscript. Dr. Alexander Krings and Dr. Jon Stucky verified specimen determinations and, along with Dr. David Lindbo, provided methodological advice and proofread the manuscript.

Suppl. material 6: List of Voucher Specimens Collected by the Senior Author
Authors: Robert Thornhill Data type: Occurences Brief description: This spreadsheet lists all specimecns (and associated data) collected by the senior author from throughout Shaken Creek Preserve, including specimens collected from the community types treated in this manuscript and from several other community types not treated here (example: swamps, roadsides, etc.). Location data for rare taxa (i.e., those listed in table 2) and for Chamaelirium luteum and all Sarracenia spp. (which face some degree of collection pressure) has been removed. The list is currently sorted to match the order of the checklist in the manuscript but can easily be resorted any number of ways, including alphabetically by taxon. Filename: List of Specimens Collected by R Thornhill_lacking location data for rare taxa.xls -Download file (494.00 kb)

Suppl. material 7: Checklist of Taxa
Authors: Robert Thornhill Data type: occurence Brief description: This file is simply a spreadsheet of the data presented in the checklist portion of the manuscript. Filename: Checklist.xls -Download file (510.50 kb)