In 2021, CPC contracted North Carolina Botanical Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.
Approximately 45 occurrences (24 drainages/watersheds) are believed extant in scattered localities in the southeast, mid-Atlantic, and, somewhat disjunctly, in the Ouachita Mountains of Arkansas. The largest population concentration occurs along the West Virginia/Maryland border, with a second large population concentration in Arkansas. The species is dependent on narrow hydrologic conditions and is vulnerable to alterations to the natural hydrologic regime, siltation and erosion, water quality reductions, disturbance and trampling, and, possibly, competition from invasive plants; land-use conversion is also a threat at some sites. Many of the occurrences are at least partially on federal or state lands, under a conservation easement, or managed for conservation, but, particularly for the riverine populations, protection/management of occupied sites alone may be insufficient to ensure persistence in the face of watershed-level threats. Also, of the five pond populations believed extant, only one is protected. A few of the riverine populations are large, but appear to be declining. Many historically-known sites have been lost; at least 25% of mapped occurrences are considered historical or extirpated.
Vulnerable to pollution of the riverine habitats where this species occurs
Susceptible to changes in stream hydrology, such as draining of its habitat or areas upstream for conversion to agricultural land, or drowning of it by stream impoundments
Approximately 10 populations remained at the time of listing (USFWS 1988); six stream populations in Alabama, Maryland, West Virginia, and North Carolina, and four pond populations in South Carolina and Georgia. However, populations were found in five counties in Arkansas in 1990 (Arkansas Natural Heritage Commission 2002).
Kress et al. studied the genetic variation of this species (1994).
North Carolina Botanical Garden has attempted to germinate seeds of this species, but have found them extremely difficult to germinate, possible because, like many other wetland plants, their seeds do not tolerate storage well.
Little is known about the habitat requirements of Ptilimnium nodosum, including the effects of fire and fire suppression. (USFWS 1991)
Continue to work on propagation protocols.
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