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D.M. Frings and L.J. Davenport
22001177 SOUTHEASTERN NATURALIST Vo1l6.( 116):,5 N9–o6. 91
Current Status of the Granite Pool Sprite, Gratiola
amphiantha (Plantaginaceae), in Alabama
David M. Frings1,* and Lawrence J. Davenport1
Abstract - Gratiola amphiantha (Granite Pool Sprite or Little Amphianthus) is a federally
threatened plant species found in solution depressions formed on granite outcrops of Alabama,
Georgia, and South Carolina. In Alabama, its distribution has recently been reduced
from 3 to 2 counties along the eastern border in 8 small pools totaling less than 10 square
meters. This study was initiated to monitor population numbers in Alabama, identify new
populations, and make recommendations for the conservation of this species. Counts of individuals
and pools were made in 2012 and 2013 at Penton (Chambers County) and Almond
(Randolph County); a third site at Wehadkee Creek (Randolph County) was added in 2016.
Numbers of individuals per pool differed dramatically; Pool P-3 dropped 72% from 2012 to
2013 before recovering partially (to -36%) in 2016. Densities were calculated for the larger
pools, with Pool A-1 reaching 32.41 plants per 10 cm² in 2016. Because of habitat loss
due to human disturbance—quarrying, recreational use, and dumping—G. amphiantha are
close to extirpation in Alabama. A recovery plan, featuring the purchases of key properties,
removal of competing vegetation, and the transferring of seed banks to additional pools,
should be immediately implemented.
Introduction
Gratiola amphiantha D. Estes & R.L. Small (Granite Pool Sprite or Little
Amphianthus) inhabits shallow vernal pools of granitic outcrops in the Piedmont
province of the southeastern United States. Originally described as Amphianthus
pusillus Torrey (1837) and maintained as a monotypic genus within the Scrophulariaceae,
it has recently been subsumed as G. amphiantha and—due to the recent
fragmentation of the scrophs—transferred to the Plantaginaceae (Estes and Small
2008). With its range restricted to Alabama, Georgia, and South Carolina (Fig. 1),
the species is currently listed as threatened by the US Fish and Wildlife Service
(Norquist 1988).
Granite Pool Sprite is a winter annual that germinates from September through
October in the very thin veneers of moist soil covering the bottoms of solution
depressions etched into granitic expanses. The initial plant forms a small rosette of
flat, opposite, linear, pointed leaves, each about 6 mm long. The pools collect rainwater
during November and December, when the plants form several thread-like
scapes growing to the pool’s surface (giving the species another colorful common
name, Snorkelwort). The scapes are terminated by pairs of opposite, ovate, floating
bracts, slightly longer and much flatter than the rosette leaves (Fig. 2). During
late winter, Granite Pool Sprites form open (chasmogamous) white surface flowers,
¹Department of Biological and Environmental Sciences, Samford University, Birmingham,
AL 35229. *Corresponding author - dmfrings@samford.edu.
Manuscript Editor: Alvin Diamond Jr.
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Figure 1. Range of Gratiola amphiantha (Granite Pool Sprite) in the southeastern United
States.
Figure 2. Floating leaves of Gratiola amphiantha (Granite Pool Sprite) at the Penton location.
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2017 Vol. 16, No. 1
4 mm across, between the floating bracts. In addition, similar-appearing closed
(cleistogamous) flowers develop from the subsurface rosette (Fig. 3). Self-pollination
of both flower types results in bilobed capsules, each 2 mm across, filled with
tiny seeds. The seeds remain dormant in the drying pools until the following season
(Allison 1993, Hilton and Boyd 1996).
The vast majority of Granite Pool Sprites reside in Georgia, especially on the
granitic domes surrounding Atlanta. The species reaches its extreme western extent
in neighboring eastern Alabama, where it once occurred in 5 locations across
3 counties of the Piedmont physiographic province: Blakes Ferry, Almond, and
Figure 3. Cleistogamous flowers of Gratiola amphiantha at the Penton location in a drying
pool near the end of a season.
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Wehadkee Creek (Randolph County); near Penton (Chambers County); and off
Thornton Road (Tallapoosa County) (Fig. 4; Keener et al. 2016). The population
at Blakes Ferry (which is now a public park) has apparently been extirpated due
to overuse for recreation; no plants were observed during a site visit over 20 years
ago (Allison 1993) nor by the authors in 2010. The Thornton Road location, first
observed in 2006 (A. Schotz, Auburn University, Auburn, AL, pers. comm.), has
long been used as a rural dump site; no Pool Sprites were found there by the authors
in 2013 and 2016.
The disappearance of Granite Pool Sprite from the above 2 sites led directly to
this study, which is part of a larger investigation of granite, sandstone, and limestone
glades in central and northern Alabama. Previous work on Helianthus porteri
(A. Gray) Pruski (Confederate Daisy) —which is known from similar glades and
outcrops—appeared in this journal (Frings and Davenport 2015).
Methods
This study began in the winter of 2010 and continued until 2016. Sites with
known Granite Pool Sprite populations were visited to verify population numbers
during the months of December through February. In addition, potential Granite
Pool Sprite sites were identified using a combination of Google Earth® and geologic
maps of the Alabama Piedmont (Neathery and Reynolds 1975, Szabo et al.
1988). While the initial studies involved simply recording the presence or absence
of Granite Pool Sprite, in 2012 we conducted a baseline survey to determine population
numbers in the pools at Penton and Almond. To ensure accurate tallies, we
placed an archeological-grade 1 m x 1 m grid over each pool to facilitate counting
Figure 4. Current range of Gratiola amphiantha (Granite Pool Sprite) in Alabama.
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(Fig. 5). To ensure consistency, only 1 of us (D.M. Frings) performed the actual
count. Because Granite Pool Sprite rosettes may send up more than one scape, only
the rosettes were tallied. Counts were repeated at Penton and Almond in 2013 and
2016. In 2016, we added an additional site (Wehadkee Creek) to the study.
We deposited voucher specimens for all sites in the Samford University Herbarium
(SAMF), Birmingham, AL.
Results
In total, we examined 7 Alabama sites for the presence of Gratiola amphiantha;
their key characteristics are recorded in Table 1. Of these sites, 5 were previously
known to support this taxon: Almond, Blakes Ferry, Penton, Wehadkee Creek, and
Thornton Road. We also searched for the species at 2 additional granitic glades,
New Harmony and Roxana, but did not find it at either location.
The Alabama populations of Granite Pool Sprite occur on several rock types:
from fine- to medium-grained trondhjemite, coarse- to medium-grained gneiss, and
quartz-diorite gneiss (for details, see Neathery and Reynolds 1975). These domeshaped
outcrops or monadnocks, of Precambrian to Paleozoic age, weather slowly,
forming shallow depressions or pools on the surface. Over time, most of these
depressions trap enough soil (and moisture) to support the successional growth of
mosses, herbaceous vascular plants, and (finally) woody vascular plants. A limited
number of depressions accumulate very little soil, retaining pools of rainwater from
autumn until early spring—perfect ephemeral habitat for Granite Pool Sprite.
Figure 5. Lead author performing annual count of Gratiola amphiantha (Granite Pool
Sprite) using an archeological grid at the Almond location.
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Table 1. Field data and presence of Gratiola amphiantha (Granite Pool Sprite) in Alabama: AT = Almond trondhjemite, RMGG = Rock Mills granite gneiss,
DCHG = Dadeville Complex Camp Hill gneiss.
Location Province County Elevation in m (ft) Formation Rock type Soil pH Voucher
Blakes Ferry Piedmont Randolph 242–255 (794–835) AT Trondjhemite - Not present
Almond Piedmont Randolph 230–255 (755–835) AT Trondjhemite 6.1–6.3 Davenport 4158
Wehadkee Creek Piedmont Randolph 234–240 (769–788) RMGG Granite gneiss Davenport 6011
Penton Piedmont Chambers 230–255 (755–835) RMGG Granite gneiss 4.4–6.9 Davenport 4157
Thornton Road Piedmont Tallapoosa 223–228 (730–749) DCHG Granite gneiss Not present
New Harmony Piedmont Tallapoosa 192–228 (629–748) DCHG Granite gneiss 6.4–6.9 Not present
Roxana Piedmont Lee 208–230 (682–755) DCHG Granite gneiss - Not present
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The Penton location consists of 3 pools on the Rock Mills granite gneiss (which
is included in the Dadeville Complex), a coarse- to medium-grained biotite granite
gneiss (Neathery and Reynolds 1975). The largest pool (P-3) is slightly greater than
1 m2; pools P-1 and P-2 are approximately 0.25 and 0.5 m2, respectively. The total
baseline population of Gratiola amphiantha at Penton dropped from 2017 individuals
in 2012 to 559 in 2013—a 72% decrease (Table 2). The total 2016 population
was 1290, a 36% drop from 2012.
It should be noted, also, that Pool P-1—which showed ~10 individuals upon visual
inspection in 2010—had no plants in 2012 and 2013. However, 15 plants were
observed in 2016. Such appearance/disappearance cycles will be discussed in the
next section.
The Granite Pool Sprite population at Almond consists of 3 pools on the Almond
trondhjemite, a fine- to medium-grained, foliated trondhjemite with abundant muscovite
or biotite and epidote (Neathery and Reynolds 1975). All 3 pools are ~1 m
in diameter. From the baseline total count of 1655, this population dropped to 1270
(-23%) in 2013; the 2016 population of 1588 was 4% below the baseline.
In 2016—thanks to a landowner’s permission—a second Randolph County population,
near Wehadkee Creek, was added to the study. Like the Penton population
(Chambers County), the glades at this location are formed on Rock Mills granite
gneiss. This population consists of 2 pools: W-1 (~0.25 m²) with 2 plants, and W-2
(~2 m²) with 724 plants.
As part of this study, we calculated the densities of Granite Pool Sprite in all
3 pools located at Almond, and the largest pool, P-3, at Penton (Table 2). These
pools are similar in size, ~1 m2 each. Plant densities were calculated by adding the
Table 2. Annual population counts and densities per 10 cm2, in the years 2012, 2013, and 2016, for
Gratiola amphiantha (Granite Pool Sprite) at each of the Alabama locations that contain current or
historic occurrences.
2012 2013 2016
Location County Count Density Count Density Count Density
Penton, Al P-1 Chambers 0 - 0 - 15 -
Penton, Al P-2 Chambers 170 8.50 184 7.36 251 -
Penton, Al P-3 Chambers 1847 26.16 375 6.20 1024 10.76
Total Penton populations 2017 - 559 - 1290 -
Almond, Al A-1 Randolph 489 13.22 407 13.13 619 32.41
Almond, Al A-2 Randolph 185 4.20 265 5.64 507 6.97
Almond, Al A-3 Randolph 981 10.94 598 8.19 462 6.73
Total Almond population 1655 - 1270 - 1588 -
Blakes Ferry, Al Randolph 0 - 0 - 0 -
Wehadkee Creek, Al W-1 Randolph 0 - 0 - 2 -
Wehadkee Creek, Al W-2 Randolph 0 - 0 - 724 -
Total Wehadkee population - - - - 726 -
Thornton Road, Al Tallapoosa 0 - 0 - 0 -
Roxanna, Al Lee 0 - 0 - 0 -
Total annual population 3672 - 1829 - 3604 -
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number of plants in each 10-cm2 block, then dividing by the number of occupied
blocks. The plant density of 26.16 recorded in pool P-3 at Penton was the highest
for the 2012 baseline study; its density dropped to 10.76 in 2016. Pool A-1 at Almond
had the highest plant density recorded, 32.41, during the 2016 survey.
As noted previously, we also checked for new and historical populations. The
Roxana site (Lee County), although known to support Confederate Daisies (Frings
and Davenport 2015), which require similar kinds of rock expanses, has no Granite
Pool Sprites. Thornton Road (Tallapoosa County), which supported one pool of
~150 individuals in 2006 (A. Schotz, pers. comm.), has none today. The Blakes
Ferry population (Randolph County), documented and described in the 1930s by
botanist Roland Harper of the Geological Survey of Alabama (Harper 1939), has
been extirpated due to vehicular traffic and recreational abuse.
An additional pool west of the current Almond population, on a huge monadnock
owned by a local church, was collected and vouchered as recently as 1984
(Keener et al. 2016). No Granite Pool Sprites have been observed there since (A.
Schotz, pers. comm.).
Conclusions
Our studies show that, in the state of Alabama, Granite Pool Sprite is currently
restricted to 3 populations inhabiting 8 ephemeral pools, totaling less than 10 m2,
located in 2 counties of the Piedmont. One of the 2 most-studied populations, at
Penton, showed wild fluctuations in numbers, dropping 72% between 2012 and
2013, with one small pool “losing” its plants temporarily. The second main population,
at Almond, also dropped significantly before “settling” at 4% below its 2012
baseline number.
Although alarming, such fluctuations can be expected. Appearance, disappearance,
and total population numbers are based on moisture regimes during late
autumn and winter. Pool populations are maintained by seed banks in their gravelly
bottoms; such banks “may be 18 times greater [in number] than the germinating
plants in a given year” (Rickard 2005:9). Some populations may also be affected
by freezing weather, with individual plants uprooted by shifting ice (B. Keener,
University of West Alabama, Livingston, AL, pers. comm.).
When present, plant densities may be extremely high. In our studies, the density
at A-1 reached 32.41 plants per 10 cm² in 2016. Such densities compare well to
those found in the robust Georgia populations studied by Hilton and Boyd (1996).
In fact, transplant studies by those 2 authors found an “ideal” density (with no
intraspecific competition) of 14 plants per 10 cm²—well within the range found at
some Alabama pools.
Based on Granite Pool Sprite population numbers and plant densities, some
of Alabama’s pools appear to be quite healthy and sustainable. However, every
population suffers a precarious existence. All Alabama populations are located on
private property, which decreases the protection afforded by the US Endangered
Species Act of 1973. In addition, each Alabama population faces additional nearby
threats. The 3 Penton pools are perched within 100 m of an abandoned quarry where
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broken glass, household trash, and ATV tracks are prevalent. The Almond pools
occupy a flat expanse near a county road, and piles of household and construction
debris are found within 30 m of the site. Even though the Wehadkee Creek site
is protected by a vigilant landowner, both pools there are located within 20 m of
the rim of an abandoned quarry. These pools also lack intact rock rims, which are
needed to restrict drainage (Rickard 2005).
Two other Alabama Granite Pool Sprite populations have been extirpated in recent
years—Blakes Ferry probably due to recreational overuse, and Thornton Road
likely due to dumping (Fig. 6). Each of the above stresses is listed and described
in the recovery plan (Allison 1993) published for this federally listed threatened
species.
In addition, Gratiola amphiantha is “stressed” by being a pioneer successional
species. As such, it requires shallow pools with little organic matter. If organic matter
increases, then enough soil develops to support its main competitor, Diamorpha
smallii Britton (Elf-Orpine or Small’s Stonecrop; Allison 1993, Hilton and Boyd
1996). As the soils deepen and retain more moisture, the depressions become vegetated
“islands” supporting a successional array of larger, dominant, shade-tolerant,
and shade-producing species; the final climax community includes trees and shrubs
(Burbanck and Phillips 1983, Burbanck and Platt 1964, McVaugh 1943, Oosting
and Anderson 1939, Quarterman et al. 1993, Shure and Ragsdale 1977). Such a
trend is currently seen at the Almond site, where Pools A-1 and A-2 support small
numbers of Elf-Orpine and several species of grasses that are forming thicker soils
Figure 6. The Thornton Road location has become a rural dump site which may have led to
the extirpation of Gratiola amphiantha (Granite Pool Sprite).
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and small mats. If this successional process continues, the Granite Pool Sprite pools
will eventually dry up.
The recent decline in the Alabama populations of Granite Pool Sprite shows potential
for extirpation within the species’ westernmost range. To prevent such a fate,
we recommend that the status of Granite Pool Sprite be reassessed—reclassified in
Alabama from threatened to endangered—and that a recovery plan be developed
specific to the state. We suggest that such a plan include: (1) securing and protecting
the glades at Penton and Almond that support its largest populations; (2) removal
of competing vegetation at Almond; (3) establishing additional populations at all
sites by the transfer of seed banks to nearby pools; and (4) conducting yearly site
surveys, as recommended for Alabama in the federal recovery plan (Allison 1993).
In addition, the second historical Almond site should be purchased as a publicly
protected area and “new” populations returned to it.
Acknowledgments
We thank Jimmy Rickson (USFWS), Steve Ginzbarg (University of Alabama), Brian
Keener (University of West Alabama), Steve Krotzer (Alabama Power Company), and Al
Schotz (Auburn University). All of these colleagues readily shared important information
on Alabama populations of Gratiola amphiantha. We also thank our 2 reviewers for their
very helpful comments and suggestions.
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