CPC Plant Profile: Little Amphianthus
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Plant Profile

Little Amphianthus (Gratiola amphiantha)

Amphianthus pusillus in flower Photo Credit: Hugh and Carol Nourse
Description
  • Global Rank: N/A
  • Legal Status: N/A
  • Family: Plantaginaceae
  • State: AL, GA, SC
  • Nature Serve ID: 138613
  • Date Inducted in National Collection: 12/01/2021

Aquatic, annual herb with two types of leaves. Floating leaves less than inch (3 - 5 mm) long, oval, paired at the end of a thread-like stem. Submerged leaves in a rosette at the top of a tiny, underwater stem, each leaf less than inch (up to 5 mm) long and with a pointed tip. Flowers less than inch (3-4 mm) long, white to pale purple, with a short tube and 5 spreading lobes; flowers are held between the floating leaves and also among the submerged rosette leaves. Fruit less than ⅛ inch (3 mm) wide, somewhat flattened, with 2 lobes. Pool sprite could be confused with water starwort (Callitriche heterophylla), which also occurs in pools on granite outcrops; its floating leaves are spoon-shaped and in whorls or rosettes rather than pairs; submerged leaves are narrow and scattered along the underwater stem.

Updates
Nature Serve Biotics
  • 05/02/2017

Restricted to granite outcrops of the southeastern Piedmont (mostly in Georgia). The habitat is limited and fragile; there is a high degree of threat from trash and debris dumping into depressions in the outcrops, off-road vehicle traffic, and quarrying. Comprehensive surveys have been conducted throughout this species' range and, as of 1994, only 57 extant populations were known. Locally, the plants may occur in high densities.

Melissa Caspary
  • 01/01/2010

granite quarrying recreational use of outcrops fire-building in pools horseback riding cattle trampling eutrophication of pools from cattle droppings development trash dumping off-road-vehicle use

Melissa Caspary
  • 01/01/2010

Georgia: Approximately 36 extant populations occur in 17 counties; of these, 8 populations are more or less protected in 7 parks and preserves; total acreage of all pools with pool sprite is less than 1 acre. Amphianthus pusillus population presence seems robust at most sites. With the exception of five sites (one extirpation at Bakers Rock and four populations declining toward extirpation Wolf Rock, Rock of Ages, Gray Rock, and Philadelphia Road), Amphianthus pusillus appears to be sustaining previous population levels (Melissa Caspary, pers. comm. 2008). Alabama: Three populations South Carolina: Three populations

Melissa Caspary
  • 01/01/2010

Melissa Caspary, Ph.D. candidate at the University of Georgia School of ecology, is researching the impacts of exotics species on granite outcrop species, including Amphianthus pusillus. Hilton and Boyd (1996) examined microhabitat requirements, density-fecundity relationships, and microdistribution of Amphianthus pusillus on a granite outcrop in Heard County, Georgia. They found that abiotic features of Amphianthus pusillus habitat varied widely, with water depth varying 93-fold and soil depth 22-fold. There was no relationship between soil depth and Amphianthus fecundity. Density and fecundity of the co-occurring species, Diamorpha smallii, also failed to correlate with Amphianthus pusillus density and fecundity. They concluded that variables considered important in defining Amphianthus habitat at a coarse scale (water, soil depth, etc.) are not as important at the finer scale at which their study was conducted. They speculate that variables such as microsite history, seed predation, and seed bank size are more important at fine scales, and that unoccupied suitable habitat exists within pools. Implications for conservation management: since suitable habitat is difficult to define and may depend on easily disturbed microsite factors, habitat manipulation is not recommended; however, sowing seeds of Amphianthus into pools known to currently or historically support the species may be successful in restoring and producing robust populations.

Melissa Caspary
  • 01/01/2010

Pool sprite populations are dependent on seasonal inundation and are destroyed by siltation and sedimentation into pools. Therefore, site management must include protection from erosion which deposits silt and debris into pools, and water diversion which leads to permanent drying. Other management recommendations include: Protect granite outcrops from quarrying, trash dumping, and off-road-vehicle use. Direct foot traffic away from rare plant sites and rock pools. Create buffers and limit development around outcrops (Chafin 2007). Traffic from off-road vehicles appears to be the greatest impact at most sites. ATVs are clearly reshaping populations at Camp Meeting Rock, Rock of Ages, Wolf Rock, and other Georgia sites. Grazing from horses and cattle can also seriously impact the pool habitat and introduce exotics (e.g. at 40 Acre Rock). Pool use by Canada geese and bobcats was also observed; it is not clear if this activity could increase eutrophication in pools and lead to population declines. Many outcrops were also observed to be used as dump sites. Impacts from trash may lead to the leaching of chemicals in pools. Within the pools, the introduction of the exotics Ranunculus pusillus and Callitriche heterophylla appear to be placing competition pressure on Amphianthus pusillus, Isoetes melanospora, and Isoetes tegetiformans. Along the margins of the granite outcrop sites, Lonicera japonica and Ligustrum sinense appear to be the major invasive threats.

Melissa Caspary
  • 01/01/2010

impact of exotic pest plants germination requirements

Melissa Caspary
  • 01/01/2010

The recovery plan(1993)recommends: preservation of genetic stock from acutely threatened populations research on germination requirements

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Photos
Nomenclature
Taxon Gratiola amphiantha
Authority D. Estes & R.L. Small
Family Plantaginaceae
CPC Number 111
ITIS 834190
USDA GRAM3
Common Names little amphianthus
Associated Scientific Names Amphianthus pusillus | Gratiola amphiantha
Distribution Piedmont of Georgia, South Carolina, Alabama
State Rank
State State Rank
Alabama S1
Georgia S2
South Carolina S1
Habitat

Shallow, flat-bottomed depressions (solution pits, vernal pools) on granite outcrops, with thin, sandy or gravelly soils and winter-spring inundation. Pools must be deep enough to hold water for several weeks and must be in full sun.

Ecological Relationships

Pool sprite is an annual that completes its life cycle seed germination, leaf emergence, flowering, fruit production, and death in just 3 - 4 weeks. In dry years, it may not appear at all, the seeds lying dormant until wetter weather. The depth or duration of water in the pools needed for germination is not known. Typically, seeds germinate following the increasingly heavy rains of late fall or early winter; young plants grow slowly during the winter but begin to form flower buds by early February. Growth accelerates as temperatures warm; the length of pool sprites stem depends on the depth of the water; the stem will continue to elongate until the paired leaves and flower are floating on the surface of the pool. By late February, flowering of both floating and submerged flowers is well underway, peaking in mid-March. As the pools begin to dry in April, the usually closed submerged flowers are exposed and begin to open. All stages of the plant may be visible in April, from buds to mature fruit, with larger plants having from 10 - 15 flowers and fruits. As the pools dry up, the fruits shed their seeds, and plants wither and disappear by late May and June. Seed dispersal has not been directly observed but likely occurs when birds and other animals walk from pool to pool on an outcrop (NatureServe 2007). Pool sprite may also produce seeds asexually, a reproductive method which reduces genetic diversity and population viability.Piedmont quillwort (Isoetes piedmontana) is the most frequent co-occurring species; other associated species include water starwort (Callitriche heterophylla) in the deeper portions of the pools and Small's stonecrop (Diamorpha smallii) in the drier areas. Where pools are disturbed, water starwort competes with and eventually excludes pool sprite.

Pollinators
Common Name Name in Text Association Type Source InteractionID

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