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Eupatorium
paludicola E.E. Schill.
& LeBlond
A distinctive new Eupatorium
(thoroughwort, boneset) has been found growing in Carolina bays
and similar wet depressions in North and South Carolina. It is
called Bay Boneset and has been identified from
eight sites in the Carolina Coastal Plain.
Botanist Richard Porcher of The Citadel was the first to notice
that this eupatorium was different, while at a bay near Kingsburg,
SC, with Patrick McMillan of Clemson University in 1998.
The description of this new species was published in LeBlond,
Richard J., Edward E. Schilling, Richard D. Porcher, Bruce A.
Sorrie, John F. Townsend, Patrick D. McMillan and Alan S. Weakley
(2007) Eupatorium paludicola, sp. nov. (Asteraceae):
A new species from the coastal plain of North and South Carolina.
Rhodora 109 (938) : 137-144.
Molecular studies by Edward Schilling at the University of Tennessee
(published in Rhodora 109(938): 145-160) have
determined not only that the newly-described plant is a distinct
species, but that it also is very likely the "mother"
of another very rare eupatorium, New England boneset, known from
15 sites in coastal Massachusetts and Rhode Island. The other
parent of the New England plant is believed to be common boneset
(E. perfoliatum).
Photographs at right and below by Bruce
Sorrie.
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What immediately sets bay boneset
apart from other eupatoriums are the narrowness and orientation of its
leaves.
Measuring only 2-4.5 mm wide, the paired,
opposite leaves ascend at an angle of greater than 45degrees from the
horizontal,
and often are erect-recurved; that is, with their tips arching back
to the stem and the two leaves forming the outline of an ellipsis.
No other eupatorium has ascending leaves that narrow.
Photo by Bruce Sorrie.
State Line Prairie Bay in Scotland County, North Carolina
The species name, paludicola, is Latin for “a dweller
in marshes.”
Bay boneset favors isolated wet depressions with fluctuating water levels,
and several of the sites are clay-based
Carolina bays with perched water tables.
The habitats are typically flooded in winter and spring, and sometimes
well into summer.
These conditions favor wildflowers, grasses, and sedges that are able
to take advantage of an often short growing season,
and discourage most shrubs and trees. However, pond cypress (Taxodium
ascendens) has been able
to produce an open canopy at some of these sites.
Other inhabitants include the very rare awned meadow-beauty (Rhexia
aristosa),
Boykin’s lobelia (Lobelia boykinii), and Hirsts’
witch grass (Dichanthelium hirstii).
  
Curriculum North Carolina UNC
In Ecology Botanical Garden Biology Department
University
of North Carolina Herbarium
CB# 3280, Coker Hall
University of North Carolina
Chapel Hill, NC 27599-3280
phone: (919) 962-6931
fax: (919) 962-6930
email: herbariumATSIGNbio.unc.edu
Last Updated: 29 August
2007
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