, a species in the milkweed family, is also known as Black swallow-wort
, Louise's swallow-wort
., or Black dog-strangling vine
, Cynanchum louiseae
is a species of plant that is native to Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and is found primarily in Italy, France, Portugal, and Spain. It is an invasive plant species in the northeastern United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, parts of the Midwest, southeastern Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, and California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
is a perennial, herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
vine with oval shaped leaves that have pointed tips. The leaves are 3-4 inches long an 2-3 inches wide and often occur in pairs on the stem. The flowers have five petals that are star-shaped with white hairs. The flowers range in color from dark purple to black. The fruit of Cynanchum louiseae
is slender, tapered pods that range in color from green to light brown.
tends to grow in upland areas and is tolerant to variable light, salt, and moisture levels. In the United States, Cynanchum louiseae
is often found in abandoned fields, hedgerows, brushy areas, woodlands, river banks, transportation corridors, quarries, agricultural fields, and gardens. In gardens, Cynanchum louiseae
is seen as a weed.
emerges in the spring and flowers during June and July. Cynanchum louiseae
is self-pollinating. Seed pods form throughout the summer. The number of pods formed is directly linked to the amount of light the plant is exposed to. If there is a higher level of light, then there are more seed pods. If there is a lower level of light, then there are fewer seed pods compared to a plant exposed to a higher level of light. Its seeds begin to be released by mid-August and continue to be dispersed into early October. Each seed is polyembryonic and contains about one to four embryos per seed. Polyembryonic seeds increases Cynanchum louiseae's
chance of survival. Seeds also use "parachutes" in order to be dispersed by the wind over large distances. In addition to seeds, for reproduction, Cynanchum louiseae
also uses rhizomes as a method of reproduction, meaning that the plant clones itself and produces new plants. After seed dispersal, the plant dies to the ground in the winter and returns in the spring.
The first group of Cynanchum louiseae
was recorded to be in Ipswich
Ipswich is a coastal town in Essex County, Massachusetts, United States. The population was 12,987 at the 2000 census. Home to Willowdale State Forest and Sandy Point State Reservation, Ipswich includes the southern part of Plum Island...
, in Essex County, Massachusetts
-National protected areas:* Parker River National Wildlife Refuge* Salem Maritime National Historic Site* Saugus Iron Works National Historic Site* Thacher Island National Wildlife Refuge-Demographics:...
in 1854. In 1864, a plant collector recorded that it was "escaping from the botanical garden where it is a weed promising to be naturalized". Thus, Cynanchum louiseae
escaped from a garden in the Cambridge
Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...
area of Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
and naturalized in the surrounding states and is still spreading today.
In the United States and Canada, Cynanchum louiseae
is a threat to native species because it crowds out native species. For example, Cynanchum louiseae
can completely replace a field of goldenrod
Solidago, commonly called goldenrods, is a genus of about 100 species of flowering plants in the family Asteraceae. Most are herbaceous perennial species found in the meadows and pastures, along roads, ditches and waste areas in North America. There are also a few species native to Mexico, South...
. Crowding out other species results in a reduced habitat for wildlife and some species may become endangered because they do not live in the correct habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. Cynanchum louiseae
threatens the rare limestone pavement barren ecosystems by crowding out plants that the surrounding wildlife needs. Cynanchum louiseae
may also decrease bird presence in grasslands, which may cause insect species populations to increase. In Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
, Cynanchum louiseae
crowds out the endangered species Jessop's milk vetch. In Rhode Island
The state of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...
, Cynanchum louiseae
reduces the effectiveness of electric fences, which may cause livestock to be put into danger or lost. In addition, Cynanchum louiseae
crowds out another species of milkweed that monarch butterflies use in order to reproduce. When monarch butterflies try to reproduce using Cynanchum louiseae
, the larvae do not survive. Thus, Cynanchum louiseae
threatens populations of monarch butterflies. Overall, Cynanchum louiseae
reproduces effectively and can easily take over various habitats in a short amount of time. It can easily take dominance over native species' habitats. Most of the possible implications of Cynanchum louiseae
changing the physical structure of various ecosystems are yet to be known.
There are four methods of management that can possibly be used for the management of Cynanchum louiseae
. These methods are chemical, manual, mechanical, and biological. Only the chemical, manual, mechanical methods are actually used in the United States and Canada. The biological method may be used in the future. Overall, early detection and removal is the best management.
The best chemical management over Cynanchum louiseae
is through the use of systemic herbicides. Systemic herbicides prevent seeds from being viable and, as a result, the next generation will not exist. Garlon 4 (tridopyr ester
) and RoundUp Pro (glyphosate
) are the main systemic herbicides that are used to control Cynanchum louiseae
. The systemic herbicide is sprayed on the plant after flowering has begun. If the herbicide is used after seed pods have formed, then the herbicide is less effective because viable seeds may form. The most effective treatment using systemic herbicides is through a cut stem application, which is applying the chemical to cut stems.
Manual management is the removal of Cynanchum louiseae
from the ground by digging up its roots so that the plant cannot reproduce.
Mechanical management is the mowing down of Cynanchum louiseae
. This method does not stop growth, but it does stop seed crops. No seed crop means no reproduction and no new generation.
Biological management is the use of Cynanchum louiseae's
natural enemies to lower the population of Cynanchum louiseae
. In the United States, Cynanchum louiseae
has no natural enemies. In its native European regions, Cynanchum louiseae
has natural enemies, such as certain caterpillars, beetles, and diseases. Researchers at Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
and the USDA are researching into the use Cynanchum louiseae's
natural enemies as a way to control Cynanchum louiseae
. The use of natural enemies is controversial because the implications of adding more non-native species to threatened areas in unknown. Using Cynanchum louiseae's
natural enemies may result in many new problems.