Did you know that invasive cattails can hybridize and become even more invasive?
The narrow-leaved cattail, native to Eurasia, is an invasive aquatic plant typically found near wetlands, marshes, lakeshores, and riverbanks. In British Columbia, it has been observed in areas such as the Squamish River estuary and parts of the Fraser River estuary. Despite its presence, little is known about its establishment level or potential to hybridize with the native broad-leaved cattail.
Last year, a paper titled “Undetected but Widespread: the Cryptic Invasion of Non-Native Cattail (Typha) in a Pacific Northwest Estuary” was published, examining the current and future distribution of non-native cattail in the Fraser River estuary and its ecological impacts. The primary author of the paper is Daniel Stewart, who is a PhD student and ecologist.
Photo credit: dinanesterkova, iNaturalist
The Fraser River estuary is a vital habitat for birds and fish, serving as Canada’s largest salmon-producing river and home to over 200,000 birds. However, the presence of invasive cattails poses a potential ecological threat to this important and diverse ecosystem. The extent of this impact is explored in the paper.
The researchers were surprised to discover that non-native cattail populations were more widespread than previously thought. In addition to the invasive narrow-leaved cattail, they identified a hybrid species called Typha x glauca, which is the offspring of the invasive narrow-leaved and native broad-leaved cattails. This hybrid was found to be well-established and more competitive than either parent species.
Photo credit: Rob Routledge, Sault College, Bugwood.org
The image above illustrates the challenges of distinguishing between the three cattail species. The native broad-leaved cattail features wider leaves, with its male and female parts located closely together. In contrast, the narrow-leaved cattail has narrower leaves, with the male parts positioned on the top spike and the female parts situated 10 to 75 mm below. The hybrid cattail, on the other hand, has slightly wider leaves than the narrow-leaved cattail, and its leaves extend taller than the flower spikes.
The researchers found that invasive cattail leaf litter had significant negative effects on the richness and diversity of a site, which suggests that the leaf litter may be an important dominance mechanism for invasive cattail. They also suggested that restoration sites are more susceptible to cattail invasion, and make the point that when one is planning a new restoration project, the presence of non-native cattail in the vicinity should be considered.
If you’re interested in learning more about invasive cattail in the Fraser River, click here to read the full paper.
Invasive cattails in the Squamish River estuary?
Narrow-leaved cattail is becoming a species of growing concern in B.C. and was recently discovered in the Squamish River estuary through an iNaturalist observation in 2023. In response, SSISC acted swiftly to stop its spread. Erin Galloway, SSISC Field Manager, shared insights on the situation: “We are fairly certain we know the distribution of invasive cattail in the Squamish [River] estuary. We are attempting to limit the spread of these patches by clipping flower heads.” However, the distribution of narrow-leaved cattail in the rest of the Sea to Sky is unknown. As Erin noted, “we will have to rely on the public and our field crew to report any occurrences they come across while out and about in the region.”
Photo credit: Rob Routledge, Sault College, Bugwood.org
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