Purple Invasion

The exponential growth of purple loosestrife, an invasive flower introduced to North America around the 1800’s, is incredible.

Multiplying quickly, purple loosestrife can max the carrying capacity of marshy and pond-like areas in the span of a year. According to Garden Know How, one plant produces approximately half a million seed a year.  Purple loosestrife’s exponential rate of growth is amazing since its seeds have an extremely high germination rate, and it has no real limiting resources.

On a graph, purple loosestrife’s original growth rate would look something like this:

However, over time, the purple loosestrife’s rate of growth peters out, looking more like this:

Though purple loosestrife has no predators, the environment it takes over only has a certain amount of resources. This acts as the limiting factor.

Unfortunately, since its only limiting factors are its environment, chemicals, and people, it continues to run rampant, destroying habitats for many kinds of wildlife.


  • sleloinvasives.org
  • www.gardeningknowhow.com/plant-problems/weeds/purple-loosestrife-info.htm
  • https://www.dummies.com/education/science/environmental-science/the-environmental-science-of-population-growth-models/


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