CPC Plant Profile: Black-spored Quillwort
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Plant Profile

Black-spored Quillwort (Isoetes melanospora)

Close-up of Isoetes melanospora Photo Credit: James Henderson
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Isoetaceae
  • State: GA, SC
  • Nature Serve ID: 159181
  • Date Inducted in National Collection: 12/01/2021

Black-spored quillwort is a perennial herb, related to ferns, with a bulb-like base and forking roots. Quillworts lack stomata and take in carbon dioxide from the soil, collecting the gas in four, long, cylindrical air chambers inside their leaves; the chambers are separated by longitudinal partitions. Black-spored quillwort leaves are 1 - 3 inches (3 - 8 cm) tall, very narrow with a pointed tip and a wide base that overlaps with other leaf bases to form a round, bulb-like underground base. Spores are produced in a cavity (sporangium) in the base of the leaf; the cavity is completely covered by a transparent membrane (velum). Dozens of black or gray female spores may be seen with 10x magnification; male spores, which are produced on separate leaves, are also present but are indistinguishable without higher magnification.

Updates
  • 09/18/2020
  • Demographic Research

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.

  • 09/18/2020
  • Propagation Research

Taylor and Luebke (1986) have published protocols for germinating spores and growing sporelings of aquatic species of Isoetes.

  • 09/18/2020
  • Genetic Research

Research was conducted in the mid-1990s (Van de Genachte 1996) to investigate the genetic diversity of Isoetes melanospora, which displays a level of gene diversity at the population level that is typical of endemic species. Populations of I. melanospora were strongly dissimilar genetically, suggesting that a large number of populations must be conserved in order to preserve most of the diversity of this species; however, the high number of extirpated populations (at least 5, possibly 10) suggests that much of the species diversityhas already been lost. I. melanospora was found to be genetically similar to I. piedmontana, with which it is known to hybridize.

Nature Serve Biotics
  • 05/02/2017

Historically known from 18 sites in Georgia and 1 in South Carolina, but due to habitat loss, now surviving at only 12 locations. Restricted to granite outcrop pools, which are rapidly being destroyed by quarrying, trash dumping, and heavy recreational use. Some important sites have been protected, but the prospects for continued existence at unprotected sites is bleak.

Linda G. Chafin
  • 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

Linda G. Chafin
  • 01/01/2010

In Georgia, 6 of the original 15 occurrences were confirmed extant in 2007, plus an additional hybrid population; additional surveys are slated for 2008 (Melissa Caspary, personal communication, 2007). According to NatureServe (2008), two populations have been historically reported from South Carolina, one from Boggs Rock in Pickens County, where only I. piedmontana has been found recently and another from Lancaster County at Forty-acre Rock. The population at Forty-acre Rock is apparently representative of another, perhaps undescribed taxon (Weakley 2006) and is not listed in the recent, thorough treatment of this group by Heafner and Bray (2005). The population at Boggs Rock does not seem to be extant, searches in 2003, 2004 and 2005 turned up only I. piedmontana.

Linda G. Chafin
  • 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. Research was conducted in the mid-1990s (Van de Genachte 1996) to investigate the genetic diversity of Isoetes melanospora, which displays a level of gene diversity at the population level that is typical of endemic species. Populations of I. melanospora were strongly dissimilar genetically, suggesting that a large number of populations must be conserved in order to preserve most of the diversity of this species; however, the high number of extirpated populations (at least 5, possibly 10) suggests that much of the species diversityhas already been lost. I. melanospora was found to be genetically similar to I. piedmontana, with which it is known to hybridize. Taylor and Luebke (1986) have published protocols for germinating spores and growing sporelings of aquatic species of Isoetes.

Linda G. Chafin
  • 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 black-spored quillwort. 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. Where appropriate and needed, repair rims of pools to slow water drainage. Consider transplanting into other pools at extant sites. Acquire fee simple ownership or easements, especially sites with larger populations. Other management recommendations (Chafin 2007) 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; eradicate exotic pest plants. Traffic from off-road vehicles appears to be the greatest impact at most sites. Grazing from horses and cattle can also seriously impact the pool habitat and introduce exotics. 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.

Linda G. Chafin
  • 01/01/2010

Protocols for the long term cultivation of plants and storage of spores have not been established.

Linda G. Chafin
  • 01/01/2010

Conserve germplasm from all extant populations. Bring species into national collection. Conduct controlled reintroduction trials. Determine effective propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Isoetes melanospora
Authority Engelm.
Family Isoetaceae
CPC Number 2346
ITIS 17136
USDA ISME3
Common Names Black-spored Quillwort | blackspore quillwort
Associated Scientific Names Isoetes melanospora
Distribution Black-spored quillwort is currently found only in the Piedmont of Georgia. Two populations have been historically reported from South Carolina.
State Rank
State State Rank
Georgia S1
South Carolina S1
Habitat

Restricted to shallow, temporarily flooded, flat-bottomed pools formed by natural erosion on granite outcrops. The pools are seasonally inundated by winter and early spring rains and by seepage from surrounding habitats; they are usually completely dry during the summer and fall.

Ecological Relationships

The pools that support black-spored quillwort have the capacity to contain water to a depth of 1 - 4 inches (3 - 10 cm); pools with shallower or deeper water are invaded by other species that outcompete black-spored quillwort and the associated rare and endangered species, pool sprite (Amphianthus pusillus) and mat-forming quillwort (Isoetes tegetiformans) (USFWS 1993). Black-spored quillwort readily hybridizes with Piedmont quillwort (Isoetes piedmontana), with which it occurs on several outcrops (Van de Genachte 1996).

Pollinators
Common Name Name in Text Association Type Source InteractionID

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