Cynanchum louiseae - Kartesz & Gandhi
Black Swallow-wort
Other English Common Names: Louise's Swallow-wort
Other Common Names: Louise's swallow-wort
Synonym(s): Cynanchum nigrum (L.) Pers. ;Vincetoxicum nigrum (L.) Moench
Taxonomic Status: Accepted
Related ITIS Name(s): Cynanchum louiseae Kartesz & Gandhi (TSN 506929)
Unique Identifier: ELEMENT_GLOBAL.2.151919
Element Code: PDASC050W0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Dogbane Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Gentianales Apocynaceae Cynanchum
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Cynanchum louiseae
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Reviewed: 26Jun2006
Global Status Last Changed: 26Jun2006
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (12Oct2016)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Connecticut (SNA), Delaware (SNA), Florida (SNA), Illinois (SNA), Indiana (SNA), Iowa (SNA), Kansas (SNA), Kentucky (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNR), Michigan (SNA), New Hampshire (SNA), New Jersey (SNA), New York (SNA), Ohio (SNA), Pennsylvania (SNA), Rhode Island (SNA), Vermont (SNA), Wisconsin (SNA)
Canada Ontario (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Endemic to southwestern Europe, primarily in the Iberian Peninsula, southern France and northern Italy. Canada distribution (invasive) includes southern Ontario and southwestern Quebec (DiTommaso et al., 2005). U.S. range (based on herbarium specimens) include: Connecticut, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Missouri, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, and Wisconsin; recently from California, Kansas, Kentucky (possibly in error), Minnesota, and Nebraska (DiTommaso et al., 2005).

Other NatureServe Conservation Status Information

Distribution
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Global Range: Endemic to southwestern Europe, primarily in the Iberian Peninsula, southern France and northern Italy. Canada distribution (invasive) includes southern Ontario and southwestern Quebec (DiTommaso et al., 2005). U.S. range (based on herbarium specimens) include: Connecticut, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Missouri, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, and Wisconsin; recently from California, Kansas, Kentucky (possibly in error), Minnesota, and Nebraska (DiTommaso et al., 2005).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States CTexotic, DEexotic, FLexotic, IAexotic, ILexotic, INexotic, KSexotic, KYexotic, MA, MDexotic, MEexotic, MIexotic, NHexotic, NJexotic, NYexotic, OHexotic, PAexotic, RIexotic, VTexotic, WIexotic
Canada ONexotic, QCexotic

Range Map
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Ecology & Life History Not yet assessed
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Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High
Rounded I-Rank: High
I-Rank Reasons Summary: Large, monospecific stands can form in open, fully-exposed areas. In brushy areas, these vines can over-top and smother shrubs, forming the dominant cover. Under forested canopies, plants of shorter stature can comprise the dominant cover in the herbaceous understory layer. The twining and sprawling habit contributes to effective contribution with pre-existing vegetation, and frequently results in large monocultures. This species has become particularly invasive in coastal areas of New England, the Connecticut River valley, and the lower Hudson River region. Adverse effects to native species (including federally endangered species) have been documented and the species has moderate invasiveness potential and is readily capable of long-distance dispersal. Management difficulty is high and time frame for management moderate with control measures having moderate effects on native species.
Subrank I - Ecological Impact: High/Medium
Subrank II - Current Distribution/Abundance: High
Subrank III - Trend in Distribution/Abundance: Medium
Subrank IV - Management Difficulty: High
I-Rank Review Date: 22Jun2006
Evaluator: J. Cordeiro
Native anywhere in the U.S?
Native Range: This species is native to western European Mediterranean regions (Lawlor, 2001). Tewksbury et al. (2002) list native distribution as southwestern Europe in France, Italy, Portugal, and Spain.

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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: This species has been established as a non-native in the United States for over 150 years in both disturbed and undistrubed upland natural areas (Lawlor, 2001).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: This species has been established as a non-native in the United States for over 150 years in both disturbed and undistrubed upland natural areas (Lawlor, 2001).

Subrank I - Ecological Impact: High/Medium

1. Impact on Ecosystem Processes and System-wide Parameters:Moderate significance
Comments: Ecosystem scale modification appears obvious but impacts have not yet been studied (DiTommaso et al., 2005; Lawlor, 2001). However, when invading open or brushy areas, appears to cause ecosystem-wide reduction in light availability for co-occurring species.

2. Impact on Ecological Community Structure:Moderate significance
Comments: Large, monospecific stands can form in open, fully-exposed areas. In brushy areas, these vines can over-top and smother shrubs, forming the dominant cover. Under forested canopies, plants of shorter stature can comprise the dominant cover in the herbaceous understory layer (Lawlor, 2001; Sheeley and Raynal, 1996). The twining and sprawling habit contributes to effective contribution with pre-existing vegetation, and frequently results in large monocultures (DiTommaso et al., 2005; Massachusetts Invasive Plant Advisory Group, 2005).

3. Impact on Ecological Community Composition:Moderate significance
Comments: This species can form dense stands that displace desirable native species and, although community dynamics studies have not been carried out, presence large mono-specific stands suggest they can suppress other plant species via competition for soil moisture and nutrients, light, other environmental factors, or via alleopathy (DiTommaso et al., 2005; Lawlor, 2001). It is known to outcompete native wildflowers and young trees (Czarapata, 2005).

4. Impact on Individual Native Plant or Animal Species:High/Moderate significance
Comments: Because this species adversely affects monarch butterfly (Danaus plexippus) populations as monarchs oviposit on black swallow-wort rather than on native Asclepias species (milkweeds) and eggs experience high mortality levels when they do (Casagrande and Dacey, 2001; Haribal and Renwick, 1998), it can be inferred that other native insects that use milkweed plants as hosts might also be negatively affected by using black swallow-wort instead (Tewksbury et al., 2002). Roots of Cynanchum vincetoxicum are considered poisionous to humans and several mammals and the same is likely true for other species in the subgenus Vincetoxicum (DiTommaso et al., 2005).

5. Conservation Significance of the Communities and Native Species Threatened:High significance
Comments: Occurrence of stands of this species are threatening the survival of rare and threatened native species, such as Jessop's milkvetch (Astragalus robbinsii) on ice scoured banks of the Connecticut River in Vermont (DiTommaso et al., 2005; Lawlor, 2001). The closely related Vincetoxicum rossicum was also observed overgrowing the federally listed Hart's tongue fern (Phyllitis scolopendrium) at Split Rock, near Onadaga, New York (Lawlor, 2001); and is also threatening the only New England population of Asclepias viridiflora in Connecticut (state endangered) (Tewksbury et al., 2002; Haribal and Renwick, 1998). This species also adversely affects monarch butterfly (Danaus plexippus) populations as monarchs oviposit on black swallow-wort rather than on native Asclepias species (milkweeds) and eggs experience high mortality levels when they do (Casagrande and Dacey, 2001; Haribal and Renwick, 1998). Further, they may pose a greater threat to monarch butterflies by reducing host plant availability through competetive displacement (DiTommaso et al., 2005).

Subrank II. Current Distribution and Abundance: High

6. Current Range Size in Nation:High significance
Comments: North American herbarium records date to 1854 in Massachusetts with collections also from New York, Michigan, Ohio, Rhode Island, Vermont, Pennsylvania, Illinois, Missouri, Connecticut, Maine, Maryland, New Jersey, New Hampshire, Indiana, and Wisconsin (Sheeley and Raynal, 1996) and recently in Kansas, Kentucky, Nebraska, and California (USDA, 1999). Tewksbury et al. (2002) cite North American distribution as extending west from the Atlantic coast to southeastern Ontario and south to southern Pennsylvania and Missouri with a record from California.

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Moderate significance
Comments: Although considered an invasive plant throughout the United States, it has become particularly invasive in coastal areas of New England, the Connecticut River valley, and the lower Hudson River region (Lawlor, 2001).

8. Proportion of Nation's Biogeographic Units Invaded:Moderate significance
Comments: It is conservatively estimated that over 25 ecoregions (disjunct in California) have been invaded by Cyanchum louiseae in the United States (Cordeiro, pers. obs., April 2006, based on TNC, 2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:High significance
Comments: Plants thrive in sunny open areas, shrub habitats and hedges, as well as under fully shaded forest canopies and is found in a wide range of upland habitats and is primarily a species of woods and moist sunny places (though it tolerates a wide range of light intensities) (Lawlor, 2001; Tewksbury et al., 2002; Uva et al., 1997). Ecologically a generalist, tolerating a wide range of light intensities, soil conditions, and habitats. It is generally an upland species, but rivers and streams that experience spring flood scouring, such as flood plain ravines along Lake Ontario and the banks of the Connecticut River near Windsor, Vermont, have been extensively invaded (DiTommaso et al., 2005).

Subrank III. Trend in Distribution and Abundance: Medium

10. Current Trend in Total Range within Nation:High significance
Comments: Cynanchum louiseae appears to be rapidly expanding its range in North America and there is no evidence theat it is near to reaching maxiumum geographic or ecological distribution; future growth is expected (DiTommaso et al., 2005). Much like in Europe (Fournier, 1977 cited in Lawlor, 2001), this species has spread across the United States over the past 150 years beginning in New England. The natural spread of most exotic Vincetoxicum species (not V. hirundinaria, though) appears to be slower, however, than other exotic plant species that colonize new sites aggressively by sexual and vegetative means. Once established, however, Vincetoxicum species may persist for decades serving as source populations for further spread; with populations in Illinois and New York sustained for over 70 years since establishment (Sheeley and Raynal, 1996).

11. Proportion of Potential Range Currently Occupied:Medium/Low significance
Comments: Cynanchum louiseae appears to be rapidly expanding its range in North America and there is no evidence theat it is near to reaching maxiumum geographic or ecological distribution; future growth is expected (DiTommaso et al., 2005). This is evident by the recent disjunct invasion in areas of California far removed from the eastern and northeastern center of its distribution in the United States. It has also become locally abundant in several areas in Wisconsin recently (Czarapata, 2005). It is particularly invasive in the northeast where it occupies all the New England states (Mehrhoff et al., 2003).

12. Long-distance Dispersal Potential within Nation:High significance
Comments: Seeds are wind-dispersed, bearing the tuft of hairs like a parachute for long-distance dispersal. Observations indicate a large proportion of seeds ramains close to the parent plant, but many small, satellite populations are often found downwind of large seed source populations (Lawlor, 2001; Czarapata, 2005). Human land management activities may also contribute to dispersal (harvesting, hay making) as this species is listed as a cultivated ornamental in the United States, sometimes incorrectly under the name Cynanchum nigrum (DiTommaso et al., 2005).

13. Local Range Expansion or Change in Abundance:Moderate significance
Comments: Although the species has been present in New England for over 150 years, it has expanded recently in Kansas, Kentucky, Nebraska, and California (USDA, 2006). Tewksbury et al. (2002) cite North American distribution as extending west from the Atlantic coast to southeastern Ontario and south to southern Pennsylvania and Missouri with a record from California. It has also become locally abundant in several areas in Wisconsin recently (Czarapata, 2005); as well as in New England (Mehrhoff et al., 2003).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Moderate significance
Comments: This species is listed as a "potential problem species" in Czarapata (2005). This species is associated with disturbances, particularly anthropogenic disturbances such as highway, rail, utility and other transportation corridors, limestone quarries, abandoned pastures and old fields, Christmas tree plantations, nursery crops, and other perennial crops (DiTommaso et al., 2005; Lawlor, 2001). Rivers and streams experincing spring flood scouring or areas subject to hydrologic extremes are also vulnerable to invasion (Lawlor, 2001). However, once established, the plant will readily move into nearby, less disturbed habitats.

15. Similar Habitats Invaded Elsewhere:Low significance
Comments: Habitat in native western Mediterranean region is slopes, copses, bushy places, and stoney, dry areas from sea level to 500 meters (DiTommaso et al., 2005; Fournier, 1977 cited in Lawlor, 2001).

16. Reproductive Characteristics:Moderate significance
Comments: Reproduction is by seed (Uva et al., 1997) or by spreading rhizomes, and shoots from the root crown of the parent plant (Czarapata, 2005). Black swallow-wort blooms June through September and is capable of self-pollination but is also pollinated by insects (Lumer and Yost, 1995; Uva et al., 1997). Fruit ripens late July in sunny locations and throughout August in shadier locations with seed production highest in full sun (2090 seeds per square meter per plant). Seeds in the genus Vincetoxicum (= Cynanchum) are also polyembryonic (more than 1 embryo per seed) and seed germination is bimodal with germination of some seeds in the fall and others in the following spring and plants can set fruits with viable seeds without a pollen vector (Lumer and Yost, 1995; Sheeley and Raynal, 1996; Czarapata, 2005). Seed bank dynamics are unknown. The confirmation of underground rhizomes suggests clonal vegetative reproductive capacity in this species and plants readily resprout after destruction of the aboveground shoot (Lawlor, 2001; Lumer and Yost, 1995). Seeds do not require either dormancy or stratification to germinate so in New York, seeds from early-maturing fruite may germinate and become established the same year before the first frost, whereas seeds from late-maturing fruits overwinter and germinate in the spring (Lumer and Yost, 1995).

Subrank IV. General Management Difficulty: High

17. General Management Difficulty:High significance
Comments: Prevention of new infestations is the best management method as this species is already widely distributed in the northeastern U.S., upper midwest and adjacent Canada and seeds are readily dispersed by wind. Eraciation of isolated plants and small patches is possible with persistence and an early detection system, but large scale infestations will require persistent effort and continuous follow-up monitoring to control (Lawlor, 2001). Mowing and hand-pulling are only effective if the extensive and deep root crowns are removed and completely destroyed to prevent resprouting. Response to herbicides varies by site and site condition. In treating whole plants or tall stems, glyphosate can be used in denegraded patches with little desirable vegetation; triclopyr ester is better in sites with desirable grasses to be conserved. In cut-stem applications, glyphosate was superior to all triclopyr amine concentrations (Lawlor, 2000 cited in Lawlor, 2001). In all cases, repeated follow up herbicide treatments are necessary. Fire alone is ineffective (Czarapata, 2005) but may be useful after herbicide control to control seedlings. Grazing is of mixed utility. Prolonged flooding is effective but negatively impacts native species (Lawlor, 2001). There are few to no native pests, diseases or other natural controls in North America (Lawlor, 2001; Sheeley and Raynal, 1996; Tewksbury et al., 2002), but there are several potential biological control agents associated with the related Vincetoxicum hirundinaria in Europe (see Tewksbury et al., 2002 for discussion).

In Europe, Cynanchum vincetoxicum is very widespread and common and several associated herbivorous insects (mostly plant specialists due to the poisionous nature of this plant) are known including the leaf eating Chrysomelidae, Chrysochus asclepiadeus and Chrysomella aurichalcea ssp. bohemic; the weevil Otiorhynchus pinastri; and three dipteran species Euphranta connexa, Contarinia vincetoxici, and Contarinia asclepiadis feeding on reproductive plant parts. In Sweden, the moth, Abrostola asclepiadis, was found to be monophagous on C. vincetoxicum but only consumed a very small percantage of foliage. The lygus bugs, Lygaeus equestris and Tropidothorax leucopterus are reported to feed on seeds of C. vincetoxicum with effect on seed production relatively minimal. Species of Cynanchum, especially C. vincetoxicum, are imprtant alternate hosts for the widespread European rust fungus, Cronartium flaccidum (and Cronartium asclepiadeum) which can cause significant reductions of foliar biomass (for more information see DiTomasso et al., 2005).


18. Minimum Time Commitment:Moderate significance
Comments: Prevention of new infestations is the best management method as this species is already widely distributed in the northeastern U.S., upper midwest and adjacent Canada and seeds are readily dispersed by wind. Eraciation of isolated plants and small patches is possible with persistence and an early detection system, but large scale infestations will require persistent effort and continuous follow-up monitoring to control (Lawlor, 2001). If herbicides are to be used (see Lawlor, 2000 cited in Lawlor, 2001) repeated treatments are necessary. Because management requires and integrated approach and resprouting regularly occurs, yearly monitoring and treatment following initial control is necessary for assessments of survival and seedling establishment (Lawlor, 2001).

19. Impacts of Management on Native Species:Moderate significance
Comments: There are few to no native pests, diseases or other natural controls in North America (Lawlor, 2001; Sheeley and Raynal, 1996; Tewksbury et al., 2002), but there are several potential biological control agents associated with the related Vincetoxicum hirundinaria in Europe (see Tewksbury et al., 2002 for discussion). Also see "general management difficulty" for information on control of various Cynanchum species in Europe.

20. Accessibility of Invaded Areas:Low significance
Comments: As this species frequently occurs on private land (often downwind from an invasion point), some access issues will arise and cooperation with landownders for management will be necessary (Lawlor, 2001).

Other Considerations: The taxonomy of Vincetoxicum/ Cynanchum has been used inconsistently. Some recognize Vincetoxicum nigrum, Vincetoxicum hirundinaria, and Vincetoxicum rossicum as introduced in to North America. Some group V. rossicum with V. hirundinaria. Different scientific names have been used. Kartesz (1994) treats V. nigrum as Cynanchum louiseae, V. rossicum as Cynanchum rossicum, and V. hirundinaria as Cinanchum vincetoxicum (see Sheeley and Raynal, 1996). This has made evaluating spread of the genus difficult. For the purpose of this assessment, Cynanchum (= Vincetoxicum) nigrum is considered synonymous with Cynanthum (= Vincetoxicum) louiseae and Cynanchum (= Vincetoxicum) hirundinaria is considered synonymous with Cynanchum (= Vincetoxicum) vincetoxicum (per DiTommaso et al., 2005).
Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 26Apr2006
NatureServe Conservation Status Factors Author: Cordeiro, J.

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Casagrande, R.A. and J. Dacey. 2001. Monarch butterfly (Danaus plexippus) oviposition on black swallowwort (Vincetoxicum nigrum). RINHews, 8(1): 2-3.

  • Czarapata, E.J. 2005. Invasive Plants of the Upper Midwest. An Illustrated Guide to Their Identification and Control. The University of Wisconsin Press: Madison, Wisconsin. 215 pp.

  • DiTommaso, A., F.M. Lawlor, and S.J. Darbyshire. 2005. The biology of invasive alien plants in Canada. 2. Cynanchum rossicum (Kleopow) Borhidi [= Vincetoxium rossicum (Kleopow) Barbar.] and Cynanchum louiseae (L.) Kartesz & Gandhi [= Vincetoxicum nigrum (L.) Moench]. Canadian Journal of Plant Science, 85: 243-263.

  • Haribal, M. and J.A. Renwick. 1998. Identification and distribution of oviposition stimulants for monarch butterflies in hosts and nonhosts. Journal of Chemical Ecology, 24: 891-904.

  • Kartesz, J. T. 1991. Accepted taxon names from 1991 checklist, as extracted by Larry Morse, TNC, June 1991.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.

  • Lawlor, F. 2001. Element stewardship abstract for Vincetoxicum nigrum (L.) Moench. and Vincetoxicum rossicum (Kleopov) Barbarich. Swallow-wort. The Nature Conservancy, Arlington, Virginia. 13 pp. Available ONLINE http://tncweeds.ucdavis.edu/esadocs/.

  • Lumer, C. and S.E. Yost. 1995. The reproductive biology of Vincetoxicum nigrum (L.) Moench (Asclepiadaceae), a Mediterranean weed in New York state. Bulletin of the Torrey Botanical Club, 122(1): 15-23.

  • Massachusetts Invasive Plant Advisory Group (MIPAG). 2005. Strategic recommendations for managing invasive plants in Massachusetts. Final Report Massachusetts Invasive Plant Advisory Group, 28 February 2005. 23 pp.

  • Mehrhoff, L.J., J.A. Silander, Jr., S.A. Leicht and E. Mosher. 2003. IPANE: Invasive Plant Atlas of New England. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT. Online. Available: http://invasives.eeb.uconn.edu/ipane/.

  • Mitchell, R.S. 1986. A Checklist of New York State Plants. New York Museum Bulletin No. 458, Albany. 272 pp.

  • Pringle, J.S. 1973. The spread of Vincetoxicum species (Asclepiadeceae) in Ontario. The Canadian Field-Naturalist. 87: 27-33.

  • Sheeley, S.E. and D.J. Raynal. 1996. The distribution and status of species of Vincetoxicum in eastern North America. Buylletin of the Torrey Botanical Club, 123(2): 148-156.

  • Tewksbury, L., R. Casagrande, and A. Gassmann. 2002. Chapter 16. Swallow-worts. Pages 209-216 in R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon (eds.) Biological Control of Invasive Plants in the Eastern United States. USDA Forest Service Publication FHTET-2002-04. 413 pp.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • USDA, NRCS. 2006. The PLANTS Database. USDA Natural Resources Conservation Service (USDA, NRCS). National Plant Data Center, Baton Rouge, Louisiana 70874-4490 USA. Available online: http://plants.usda.gov. Accessed: March 2006.

  • Uva, R.H., J.C. Neal, and J.M. DiTomaso. 1997. Weeds of the Northeast. Cornell University Press: Ithaca, New York. 397 pp.

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