Pluchea odorata
(L.) Cass.
Common Name:
Sweetscent
Synonyms and Other Names:
Pluchea petiolata Cassini, Pluchea senegalensis Klatt, Pluchea purpurascens (Swartz) DC., Conyza odorata L., Pluchea purpurascens (Swartz) de Candolle var. succulenta Fernald, sweetscent, sweet scent, marsh fleabane, salt-marsh fleabane, shrubby camphorweed
Identification:
This species has several leafy branches on the upper part, none below. Leaves vary, some long and narrow, and some broad at the base, 2–4 inches long, pointed at the tip, and irregularly toothed on the margins. Flowers grow in small heads in a flat-topped cluster at the end of the stems, and are a bright pink-purple. Two subspecies exist: P. odorata v. succulenta has larger flowers and involucres 5–6 × 7–10 mm, with functionally staminate florets (14–34). Flowers of this subspecies are somewhat more pigmented and stronger scented, and native bees, flies and wasps seem to get drunk on it. The foliage smells of camphor when touched, even when dry.
Size:
20-200cm
Native Range:
The Atlantic coast.
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This map only depicts Great Lakes introductions.
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Great Lakes Nonindigenous Occurrences:
Two distinct varieties have invaded the Great Lakes. Earliest Great Lakes basin records for both subspecies are in the Detroit vicinity -- Pluchea odorata v. odorata in 1912 and Pluchea odorata v. succulenta in 1914. Both subspecies tend to be reported first in areas with high salt deposits.
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Pluchea odorata are found here.
Table last updated 5/1/2024
† Populations may not be currently present.
Ecology:
This erect shrub can grow in salt of brackish marshes along the coastlines, but can also be found in freshwater marshes and moist drainages (Cooperrider and Galang 1965, Reznicek et al. 2011, eFloras.org 2013). It blooms from August to October (eFloras.org 2013). Plumed seeds may be distributed by wind, and the plants themselves may spread rhizomatically. Plant growth is directly correlated with moisture content. This species is both heat and cold-tolerant and its aromatic foliage makes it resistant to deer and other herbivores.
Means of Introduction:
Accidental release.
Status:
Established where reported.
Great Lakes Impacts:
Current research on the environmental impact of Pluchea odorata in the Great Lakes is inadequate to support proper assessment.
Pluchea odorata var. succulenta has invaded high marsh ecosystems in New York (Lamont and Stalter 1991). Pluchea odorata is capable of hybridizing with P. indica to produce Pluchea X fosbergii (Cooperrider and Galang 1965). There is little or no evidence to support that Pluchea odorata has significant socio-economic impacts in the Great Lakes.
No significant negative economic impacts have been reported for this species.
There is little or no evidence to support that Pluchea odorata has significant beneficial effects in the Great Lakes.
The leaves and stems of P. odorata have been used medicinally in Africa, India, and the Caribbean, where it is used in medicinal tea as a mild stimulant, vasodilator, and antispasmodic (King-Jones 2001). Extracts of P. odorata have been shown to heal wounds, reduce inflammation, and inhibit the growth of cancer cells (Gridling et al. 2009, Seelinger et al. 2012).
Management:
Regulations (pertaining to the Great Lakes)
In Pennsylvania, P. odorata is listed as an endangered species ((NRCS) 2012). Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Biological
The fruit fly Acinia picturata has been known to use P. odorata as a host, but it is unknown if this species could be used a biological control agent (Stegmaier Jr. 1967).
Physical
There are no known physical control methods for this species.
Chemical
There are no known chemical control methods for this species
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
The larger size of the heads of Pluchea odorata var. succulenta (versus var. odorata) is correlated with the greater number of functionally staminate florets. The two taxa apparently intergrade across a wide area, from southeastern Virginia through South Carolina, and identifications are arbitrary in that region. In the Carolinas, heads appear to be smaller (even heads with relatively numerous florets), and in northern localities (Virginia northward) the smaller size of plants may simply reflect a shorter growing season. It may be more realistic to identify plants of all localities simply as P. odorata, noting that a trend toward increasing head size occurs northward along the Atlantic Coast.
References
(click for full reference list)
Other Resources:
Author:
Cao, L. L. Berent, and R. Sturtevant
Contributing Agencies:
Revision Date:
8/8/2019
Citation for this information:
Cao, L. L. Berent, and R. Sturtevant, 2024, Pluchea odorata (L.) Cass.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=3267&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 8/8/2019, Access Date: 5/1/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.