The following Participating Institutions are custodians for this species in the CPC National Collection:
New England Wild Flower Society
The conservation of Panicum hirstii is fully sponsored.
Elizabeth J. Farnsworth contributed to this Plant Profile.
Panicum hirstii is a stiffly erect panic grass that grows 20 - 60 cm (8 - 23 in) tall. The taxon inhabits sandy pine woods and pond shores of the coastal plain barrens of New Jersey, Delaware, and North Carolina. It is also found in limestone depression ponds and shallow Cypress ponds of Georgia. Threats to this species come mainly from habitat alteration for development and changing hydrology of coastal ponds.
Research and Management Summary:
Taxonomic work and germination studies have been performed for this species, and some monitoring of populations has occurred.
Panicum hirstii grows from clustered culms. The inflorescence, or panicle, is 3-10 cm (1-4 in) long and sparsely flowered with finely hairy spikelets; panicles sometimes stay hidden among the densely branched stems. The leaf blades are 3 - 12 cm (1 - 4.7 in) long and 2 - 7 mm (0.08 - 0.3 in) wide and variably smooth or hairy.
Distribution & Occurrence
- New Jersey
- North Carolina
Panicum hirstii occurs in sandy, coastal plain areas that undergo rises and falls in water level. Among its habitats are: coastal plain ponds in the New Jersey pine barrens; limestone depression ponds and shallow Cypress ponds in Georgia; and maritime wet grasslands of North Carolina (Amoroso 1999).
According to notes of J. R. Swallen (quoting the discoverer, Frank Hirst), the type specimen of Panicum hirstii came from a "small woodland pond in the pine barrens -- growing in the water, much as Panicum spretum often does. This is a most interesting pond, the Panicum being associated with Lobelia boykinii, Paspalum dissectum, Coreopsis rosea, etc." (Swallen 1961: 235-236). Other collections have been made in 1900 from the margin of a pine-barren pond, Sumter County (Georgia), and in 1947 from a Cypress swamp, Calhoun County (Georgia), according to Swallen (1961).
|One population in Delaware and two in North Carolina are known to be extant and vigorous. Populations at the New Jersey sites have declined significantly in recent years to just a few flowering stems (NatureServe 2001). The total global population is estimated at less than 1000 individual plants (NatureServe 2001).|
Conservation, Ecology & Research
As a member of the flora of coastal plain ponds and other seasonally wet depressions, the biology of this species is likely to be tightly tied to the variable hydrological regime that is characteristic of these areas. Population numbers fluctuate dramatically from year to year (NatureServe 2001), as is typical of the species endemic to these habitats.
Pollination of this small-flowered grass is likely to be via wind. The species apparently can form a seed bank (NatureServe 2001). For more on the ecology of coastal plain ponds of the region, see Schneider (1994).
Taxonomic work on the species is ongoing. Although the taxon was first described as Panicum hirstii by Swallen (1961), Kartesz (1999) has placed the taxon into Dichanthelium while maintaining its distinct species epithet, a placement that accords with other research (Schuyler 1996). Richard LeBlond, Inventory Specialist with the North Carolina Natural Heritage Program is further investigating the taxonomy of the Panicoid grasses for the North Carolina flora. Writing in 1991 (unpublished), LeBlond said that the variability in characters suggest "the possibility of a topoclinal relationship between Panicum neuranthum and P. hirstii, the two diverging genetically and in habitat preference northward from Florida to New Jersey [however] the combination of wider autumnal leaves and included autumnal panicles in Dicanthelium = P. hirstii does not occur in any other Dicanthelium entity."
The New England Wild Flower Society (Framingham, Massachusetts) has collected seeds, but despite repeated attempts, has not been able to germinate seed successfully.
Experiments with culms grown from collected seed on how local hydrology, inundation depth, and water chemistry affect seed germination, seedling establishment, and plant reproduction.
Analysis of genetic homozygosity levels in isolated populations
Clancy, K.; McAvoy, W.; Rothstein, D.; Trew, L. 1993. Coastal Plain Ponds. Outdoor Delaware. 2, 13-17
Schuyler, A.E. 1996. Taxonomic status of Panicum hirstii Swallen. Bartonia. 59: 95-96.
Swallen, J.R. 1961. A new species of Panicum from New Jersey. Rhodora. 63, 751: 235-236.