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Araps, A - Purple loosestrife

Page history last edited by PBworks 16 years ago

 

 

Purple Loosestrife

 

Lythrum salicaria L.

 

 

OVERVIEW: Purple loosestrife, also known as spiked loosestrife, is a perennial wetland herb from the Loosestrife family (Lythraceae). It is commonly found in wetlands. A square wooded stem holds it’s opposite leaves that are lance-shaped, without stalks, and heart shaped or rounded at the base. Flower spikes protrude from the plant with each flower containing 5 to 7 petals. The whole plant is generally covered in a downy pubescence or short hairs. Loosestrife plants grow between 4 and 10 feet high and the crown can reach 5 feet wide. Mature plants can have 30 to 50 stems projecting from a single rootstock. The plant is intriguing because of its beauty in color and its invasive nature.

 

Flower of purple loosestrife

 

Source: Purple Loosestrife. [internet]. [updated 2006 Jun 27]. Plant Conservation Alliance, Alien Plant Working Group. [cited 2007 Feb 17].  Available from: http://www.nps.gov/plants/ALIEN/fact/lysa1.htm

 

 

 

 

BACKGROUND: The name Lythrum salicaria came from a Greek medicinal man of Nero’s army who referred to the plant as Lytron, Greek for blood. Loosestrife leaves closely resemble willow leaves (Salix spp.) earning the name salicaria. Purple Loosestrife is of European origin, introduced to Northern United States and Canada in the 1800s for ornamental and medicinal purposes. More specifically the plant was used as a medicinal herb for diarrhea, bleeding, dysentery, wounds, sores and ulcers. Some, however, was brought over as a contaminant of European ship ballasts.

 

 

REPRODUCTION: Purple loosestrife can be deemed infamous for its reproductive capacity. A mature plant has the capability of producing up to 2.7 million seeds. The seeds are about the size of ground pepper. High temperatures >20 degrees Celsius along with open, moist soils are needed for germination. Water dispersal occurs through floating seedlings and floating ungerminated seeds and while the seeds are light weight enough to be carried by wind, there is little evidence wind dispersal occurs regularly. Animals disperse seeds that cling to them or by digesting them.

 

 

Purple loosestrife also reproduces vegetatively through underground stems that contain adventitious buds with the capability to produce shoots or roots. Many stems can come from a single rootstock of the previous year. Single root and stem segments can create new flowering stems.

 

 

LIFE HISTORY: An herbaceous perennial, purple loosestrife plants produce their two to three million seeds annually. The plants come from one woody rootstock and produce many stems. The flowering period occurs from June to September. This extended season allows for a large quantity of seed production. Flowers produce a copious amount of nectar for required pollination by insects.

 

 

HABITAT: Wetlands such as marshes, bogs, and wet prairies, freshwater wet meadows, river and stream banks, reservoirs, pond edges, and ditches.

 

 

DISTRIBUTION: Native range originated in Europe and Asia, spreads from Great Britain across central Europe through Russia, Japan, China, Asia, and northern India. According the U.S. Fish and Wildlife Services, Purple loosestrife can be found in every state across the nation except Florida.

 

 

 

 

Native origin of purple loosestrife - darker yellow to blue area  denotes origin

 

Source: Simplicity [internet]. [updated 2008 Jan  6]. [cited 2008 Feb 18]. Available from: http://www.nationsonline.org/maps/continents_map_sm.jpg

 

 

ECOLOGICAL THREAT: The negative impact of the plant is due to its invasive nature. It adapts easily to natural and disturbed wetlands. Purple loosestrife is invasive and competitive replacing native grasses, sedges, and other flowering plants. Dense, homogenous stands alter the ecosystem killing off native species and reducing the habitat for both waterfowl and nesting ducks.

 

 

 

Overgrowth of plant – invasive nature

 

Source: Lythrum Salicaria Purple Loosestrife [internet]. [updated 2004 Jun 16]. The Western Aquatic Plant Management Society; [cited 2007 Feb 18]. Available from: http://www.wapms.org/plants/purpleloosestrife.html

 

 

The following is a map of where purple loosestrife is invasive in the U.S.

 

 

 

Source: Information from Swearingen, J. 2006. WeedUS database, Alien Plant Invaders of Natural Areas. Plant Conservation Alliance, Alien Plant Working Group. http://www.nps.gov/plants/alien/list/WeedUS.xls

 

 

INTERESTING FACTS: Currently, purple loosestrife is most commonly used for ornamental purposes in the U.S; however, there are a few states where it is banned for sale, purchase, and distribution: Illinois, Wisconsin, and Minnesota. Purple loosestrife also has an unusual method of mating termed tristyly. This term was used because of the plants three different forms of stamen and style (short, medium, or long). This system of mating promotes out-crossing which increases genetic diversity and can lead to a larger number of individuals who bear a disease recessively.

 

 

 


 

 

 

Purple Loosestrife: Lythrum Salicaria

 

            Purple loosestrife, also known as spiked loosestrife, is a perennial wetland herb from the Loosestrife family (Lythraceae). The plant is of Eurasian origin, and was brought over to the United States in the late 1800s for ornamental and medicinal purposes such as diarrhea, bleeding, dysentery, wounds, sores and ulcers. Some was brought over as a contamination of European ship ballasts. According the U.S. Fish and Wildlife Services, Purple loosestrife can be found in every state across the nation except Florida.

 

            A square wooded stem holds the plants opposite leaves that are lanceolata, long and wide in the middle, and either heart shaped or rounded at the base. The leaves bear no stock. Flower spikes protrude from the plant with each flower containing five to seven petals. The whole plant is generally covered in a downy pubescence, simply stated as short hairs. Loosestrife plants grow between four and ten feet high with a crown can reach up to five feet wide. Mature plants host 30 to 50 stems projecting from a single rootstock.

 

            Purple loosestrife is native to the major habitat of Temperate grassland, Savannahs, and Shrublands, while it currently thrives in many types of wetlands. Cattail marshes, fresh water wet meadows, open bogs, and many different marsh types are a few common areas. River and stream banks, pond edges, lakeshores, reservoirs, and even ditches can be home to the plant. Recent soil disturbance creates an even better habitat while purple loosestrife can survive in a wide range of soils such as clay, sand, and silt. The plant has the ability to survive the shade, but is generally found in full sun.

 

            Easy morphological adjustments to varying wetlands and conditions have allowed purple loosestrife to become an invasive species. As the plant expands in an area, it out competes many native plant species such as grasses and other flowering plants. This also hurts wildlife in the area by killing off its vegetation and changing habitats in which waterfowl and other wetland animals reproduce.

 

            It is a combination of the plants high seed viability means and numerous ways of seed dispersal that make it so dominating. A mature plant has the ability to produce upwards of 2.7 million seeds. The seeds are about the size of ground pepper. Water is used as the main source for dispersal while the light weight of the seeds allows for them to be carried by the wind, though there is little proof that this is common. Animals may digest the seeds or unknowingly carry them to a new destination.

 

            The first known control methods used on purple loosestrife took place in the mid 1900s and included mowing, crushing, flame torching, hand pulling, and chemical treatment. Sodium chloride and chlorate were used with little effect and mowing proved to be the best option. Water level change, burning in water, and cutting both at the surface and below the surface proved also to be ineffective. Several different herbicides were tried and while three produced a hundred percent top kill, the rootstocks were still able to regenerate. To this day a three acre or more area of purple loosestrife is said to be impossible to kill.

 

            Currently, the best known option to deal with large areas of purple loosestrife is to contain them by hand pulling or spraying herbicides on the plants along the outside of the population. There are three insect species that have been authorized by the U.S. Department of Agriculture to use as biological control agents. These insect species have not been observed to eliminate populations entirely. Glyphosate is the most commonly used herbicide to control purple loosestrife. Caution must be used however as over-spraying may cause native species to die off. Hand-pulling of the plants is most recommended for small populations. Pulling the plants before the seed sets is the best means of ensuring they do not return. Pieces of roots can regenerate into new plants so pulling the entire rootstock is essential.

 

            The invasive tendencies and high growth rate of purple loosestrife will keep it as a threat to wetlands and their native plant and animal species in the United States. While biological control, by means of pests, seems to be the best option for control, it must be carefully considered. Native species may also be susceptible. Reducing the population by at least 75% has shown to make the species manageable. Targeted biological control to achieve a desired density may be the best method to cope with the invasive purple loosestrife.

 


Bibliography

 

 

Purple Loosestrife. [internet]. [updated 2006 Jun 27]. Plant Conservation Alliance, Alien Plant Working Group. [cited 2007 Feb 17].  Available from: http://www.nps.gov/plants/ALIEN/fact/lysa1.htm

 

 

Lythrum Salicaria Purple Loosestrife [internet]. [updated 2004 Jun 16]. The Western Aquatic Plant Management Society; [cited 2007 Feb 18]. Available from: http://www.wapms.org/plants/purpleloosestrife.html

 

Heidorn R 1990. Vegetation Management Guide: Purple Loosestrife (Lythrum salicaria L.). [internet]. [cited 1990 Jun 6]. Vol 1 (17). Available from: http://www.inhs.uiuc.edu/chf/outreach/VMG/ploosestrife.html

 

Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria) in North American Wetlands. [internet]. [updated 2006 Sept 22]. U.S. Geological Survey. [cited 2008 March 2]. Available from:http://www.npwrc.usgs.gov/resource/plants/loosstrf/case.htm

 

 

 

 

 

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