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Recent reports of green matter floating on the Trent River led the Riverkeeping team on a factfinding mission to identify the material.

“Warm temperatures combined with the fact we’ve been in a long period of drought and recent intermittent storms have likely have caused an influx of nutrient-rich stormwater into our waterways,” said Pamlico-Tar Riverkeeper Katey Zimmerman. “And Duckweed and Alligator weed, as well as algal blooms, thrive in nutrient-dense waters, warm temperatures and more stagnant water, which is what we’ve been seeing.”

How to tell the difference?

Duckweed and Alligator weed are both aquatic plants, but differ in the size of their leaves and root systems. Duckweed is free-floating, has really tiny leaves and microscopic roots. Alligator weed has larger leaves and a much thicker root system underneath the surface-level mat of vegetation.

“Alligator weed is invasive, really fast-growing and very common to see,” Katey said. “Alligator weed is the hardest one to remove. You could do a physical, mechanical removal, but since it has such a dense root system, if you don’t get all of it, it could grow back. But the thing about floating aquatic plants is they don’t stay in one place for long.”

She said since Duckweed occurs naturally, it’s fine to simply let it be. Algal blooms, however, should always be reported.

The way to tell the difference between the three is by sight and the “poke test.”

Alligator weed has larger leaves than Duckweed; Duckweed might look more like an algal bloom, but it has tiny leaves.

“If you’re able to get up close to the water, algal blooms tend to have more of a slimy texture, while Duckweed is tiny plants,” Katey said. “If you poke it and it separates and stays separated, then it’s Duckweed.”

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