Purple Loosestrife: genetics and plasticity of native European and non-native American populations. A common (roof) garden experiment.

Special Feature: The Roof of Boyden Hall & the Invaders


The purple roof on Boyden Hall: A pretty plant or an ugly invader?


Purple Loosestrife, the poster child for the science of biological invasion, is both of these.


Pretty Flower!

An invaded wetland in Massachusetts


Purple Loosestrife (Lythrum salicaria) is a European wetland plant with showy magenta flowers that since the 1800s has been introduced to many parts of North America and has since became an aggressive invader of wetlands.  As it severely changes wetland ecosystems and out-competes a score of native wetland plants, it is now ranked among the most problematic invasive species in North America. 


While the species is quite well-studied, our understanding of its invasiveness is still unsatisfactory.  Even though biologist are now intensively studying the phenomenon of biological invasions, that is the spread and detrimental effects of non-native species, little general understanding has been gained on the question why some species, plants and animals alike,  turn into “ugly invaders” once they reach foreign shores.  Important clues are expected to be found when comparing such invasive species “at home” and its new homeland.  However, there has not been a comprehensive comparative analysis of purple loosestrife in its native range versus invaded ranges.


Iowa, USA

New Jersey, USA

Tubingen, SW Germany

Potsdam, NE Germany



With this in mind, a group of German and American scientist banded together and embarked on a large scale comparative, cross-continental experiment to find out whether the invader changed in it new range.  For this, plants from two regions in Germany, from New Jersey and from Iowa were collected as seeds and planted in large so called “common gardens”.  These gardens are placed in all of the four regions, so that all different plant origins are present in each garden location.  The space we found in Newark happened to be the roof of Boyden Hall of Rutgers University.



Any growth differences we will find between the origins will be the consequences of genetic differences.  We predict that American plants will grow to larger size and also will be more successful in contrasting environments (i.e.,  they are Jack-of-all-trades).  These predictions stem from hypotheses about the spread of invasive plant species that suggest that species may have evolved into superior competitors in their introduced range (e.g., the Evolution-Of-Increased-Competitive-Ability hypothesis) since they left their natural enemies behind and also escaped old competitors. 


The “common garden” on the roof of Rutgers University’s Boyden Hall, and in this is identical to gardens in Iowa and Germany, is a strange garden indeed.  Altogether 240 plants growing in groups in small wading pools that are grouped into distinct blocks.  Their growth and flowering is carefully monitored by a crew from our lab.  Soon all of them will be in full flower and it will become clear to all that working with nasty invaders can be pleasing to the eye.



"Real Time" Gallery

May, 2 2006
June,29 2006
July, 19 2006
July, 25 2006


To be continued...

For instance don’t miss the next chapter in which “Fusion Ecology Lab Member” Vincent Koczurik, answers the burning question “Where, in downtown Newark, do all the honey bees come from?”.


Send email to holzapfe@andromeda.rutgers.edu for questions or comments
Copyright © 2006 Fusion Ecology Lab
Designed by Jack A. Chapman
Last modified: 04/26/2012