The Fight of Purple Loosestrife: North America
By: Jake Melton
November 20, 2009
The Robertson’s have just moved in, there are some beautiful, luscious, purple flowers across the street so; they decide to plant them around their new pond. This plant is the awful, yet beautiful flower: purple loosestrife, an invasive species. Yet, the Robertson’s have no clue what they’re getting themselves into! Invasive species are a horrible thing. The definition of an invasive species is: an organism that harms, or has the potential to harm an environment where the plant did not originate. Sometimes species with this definition can be brought non-intentionally or, possibly intentionally. Sometimes an organism, such as the zebra mussel could latch onto a boat, or get sucked into a boat’s ballast, brought from the sea, and brought into Lake Michigan. In these situations the human did not mean to bring these zebra mussels across, yet they did. Now, let’s say that some scientist figures out that a whale, for example, can kill these dreadful zebra mussels, so they bring in a whole bunch of whales, but these whales just do the same thing as the zebra mussels, invade. So, the scientists have gotten rid one problem, and have started a whole other problem. These scientists intentionally brought in the whales to destroy the zebra mussels; this is a case where humans intentionally brought in an invader. An ecosystem can be harmed by invasive species. One way this could happen if, let’s say a zebra mussel, comes in and eats all of the plankton. If all the plankton die out every animal that eats the plankton are now without food and could starve to death. This tragic accident would make the whole food web collapse. Well, you might be asking: why don’t people just destroy all these invasive species? First, usually an invasive organism is plentiful in number and cannot be overtaken by humans. Second, people do try, for plants they try to burn, mow, or even desperately hand-pull. Just a few examples of these invasive species are organisms such as asian carp, cane toad, garlic mustard, zebra mussels, and africanized honey bees.
The purple loosestrife’s natural habitat is throughout Great Britain, in Central and Southern Europe, Central Russia, Japan, Manchuria, China, Southeast Asia, and Northern India. These areas are more generally flat and swampy; the climates of these regions are moist. Most moist locations, such as fresh water marshes, fens, sedges, meadows, and wet prairies, along with roadside ditches, river and stream banks, reservoirs, and even the edges of road sides can hold purple loosestrife. This plant is also rather shade tolerant, being able to survive in up to 50% shade. Leaf eating insects along with three species of beetles: are purple loosestrife’s natural predators.
Lythrum salicaria, or purple loosestrife is an herbaceous perennial plant with five to seven lance shaped, rose-purple flowers that are opposite or in whorls of three that produce over 2 million seeds annually. Some other distanced characteristics of purple loosestrife are the erect, 4-sided stems that flower in early July to early September. These plants can range from two to eight feet tall; averaging out at about five feet a plant, each with a stiff stem. On larger plants the base of the purple loosestrife appears woody. Each rootstock can have as many as 30 to 50 stems growing. Purple loosestrife has a very vicious “attitude”, outcompeting, and taking over other plants and their habitat. This plant replaces grasses, sedges, and other flowering plants. Loosestrifes natural instinct allows it to grow thick, dense, homogeneous strands that restrict other native species. On the other hand purple loosestrife provides a great supply of pollen for pollinating insects.
Purple loosestrife was introduced into the east coast of North America, not to be a bad plant. The Europeans, who brought purple loosestrife over brought it for medicinal uses. They also brought it over to be ornamental, because this plant is very beautiful; so purple loosestrife was obviously not brought over to harm anything, but in fact to be of good use.
Scientist’s are doing their best to prevent the spread of purple loosestrife. This task proves extremely hard. One way they are trying to prevent this is trying to burn them. A second way they are trying to prevent the spreading of purple loosestrife is mowing it. They are trying to cut them all down before they can spread. They are even trying to hand pull them, this is probably the hardest.
So, all over Europe and Asia this plant is a good plant that causes no harm, and the Europeans intended it to be that way in America. Yet, this plant is causing harm and scientist are trying to stop purple loosestrife’s spread by burning, mowing, manipulating the water level, applying chemicals, using biological control, and even hand pulling, and hopefully they will succeed.