Most people call them cattails, although you’ll come across those who refer them as “punks” or even as “corn dog grass.” If you happen to be British, you’re more likely to call them “bulrushes” or “reedmace.” They are members of the scientific family of Typhaceae, large marsh plants sporting the telltale brownish compact “flower” that some think looks like a hot dog or sausage. They are one of the most common plants you’ll find in the northern hemisphere in wetlands like marshes and ponds. And therein lies the problem. Unlike some of the other worst water weeds I’ve written about here, cattails are not exotic. They are native and meant to be part of the wetland ecosystems where they occur. But just because they’re native doesn’t mean they aren’t invasive.

This is where it’s useful to mention what we mean by the word “weed.” The simplest definition is this: A weed is any plant growing in a place where you don’t want it. Having a few cattails on the edge of your favorite pond is no big deal. But under the right conditions, cattails can spread quickly and become problematic.