Native or invasive? The easy trick for identifying cattails

At first glance, cattails all look pretty much the same. But if you take a closer look at the flower spike, one small detail can tell you whether you’re looking at broadleaf cattail or narrowleaf cattail.

The flower spike is made up of two parts. The upper section is the male portion, which produces pollen. Below it is the female portion, which develops into the familiar brown “corndog” that many people simply think of as the cattail.

The easiest way to tell the two species apart is to look where those two sections meet.

Broadleaf

On broadleaf cattail (Typha latifolia), the male and female portions usually touch or are separated by only a tiny space. From a distance, they often appear to be one continuous flower spike.

Narrowleaf

On narrowleaf cattail (Typha angustifolia), there is usually a noticeable gap between the male portion on top and the brown female portion below. Once you notice that gap, it’s surprisingly easy to spot.

Like any rule in nature, there are exceptions. Broadleaf and narrowleaf cattails sometimes hybridize where they grow together, so you may occasionally come across plants that don’t fit neatly into either description. Even so, the presence or absence of that gap is still one of the most useful field marks for identifying the two species.

Why the Difference Is Important

Broadleaf cattail (Typha latifolia) is native throughout much of North America and is an important part of healthy wetland ecosystems. Its dense stands provide nesting sites and cover for birds, shelter for amphibians, and habitat for countless insects and other wildlife. Beneath the water, its extensive root system helps stabilize wetland soils, slow water movement, and trap sediment.

Healthy wetlands are made up of many different native plants, not just one. Sedges, rushes, bulrushes, flowering plants, shrubs, and cattails all provide different sources of food and shelter for wildlife. That diversity also helps wetlands filter water, reduce flooding, and support a wide variety of insects, fish, amphibians, birds, and mammals.

Narrowleaf cattail (Typha angustifolia) is an introduced species across much of North America. In many wetlands, it spreads aggressively into dense stands that crowd out many of those native plants. Of course, nothing in nature is simple and even narrowleaf cattails can provide some benefits. However, as plant diversity declines, so does the variety of habitat available for the wildlife that depends on it. Over time, a wetland that once supported a rich mix of native species can become dominated by a single invasive plant.

The next time you’re walking along a marsh, pond, or roadside ditch, take a closer look at the flower spike. If the brown female portion sits directly beneath the male portion, you’re probably looking at broadleaf cattail. If there’s a clear gap between them, chances are you’ve found narrowleaf cattail.

One quick note: this field mark is easiest to see while the flower spike is still intact. Once the spike begins to break apart and release its seeds, the gap can become much harder to see.

About the Author:
Sabrina Halvorson is an award-winning journalist, author, and UMN Extension Master Naturalist. She serves as president of the Wild Ones Lake Agassiz Region seedling chapter, is appointed to the World Agriculture Forum, and was named the 2024 NAFB Farm Broadcaster of the Year. Learn more at sabrinahalvorson.com.