In the Midwestern United States, Typha x glauca is a hybrid of the native Typha latifolia
and the non-native Typha angustifolia. Typha x glauca is considered invasive, and it is
dominating Typha latifolia when they co-occur. Wetlands in the Midwest face nutrient
pollution, due to fertilization used within the agricultural industry. Wetlands are nutrient
sinks, which store the increased levels of nitrogen and phosphorus. These nutrients are
known to increase Typha growth. Within this thesis, it was hypothesized that an increase
of nitrogen in the wetland may increase the width of Typha leaves, making it difficult to
distinguish the native Typha latifolia from the invasive Typha angustifolia and Typha x
glauca. Other factors that may affect leaf width, such as the length of the leaf and
whether or not the ramet was flowering were also analyzed. It was found that leaf length,
nitrogen levels, flowering status, and taxa significantly impacted the leaf width of Typha
taxa, making leaf width alone an unreliable identifier in the field.
A secondary potential cause of Typha invasion was examined through a
simulation using the wetland modeling program MONDRIAN. Through MONDRIAN, the
effects of differing nitrogen levels and rhizome branching probability in both
monocultures of Typha and in a scenario with five different theoretical Typha taxa in
competition with one another were analyzed. Typha taxa with a low rhizome branching
probability had a higher growing season stem density and net primary productivity under
high nutrient conditions than taxa with a high rhizome branching probability, regardless
of whether taxa are grown in monoculture or in competition with one another.