They look like some miniature Stars-Wars-villain spaceship: a somewhat triangular-shaped pod with three black spikes. Such are the seeds of Eurasian water chestnut. Eurasian water chestnut clogs parts of the Hudson River and is on the state’s most-wanted aquatic invasive-plant list.
And the seed pods are seemingly everywhere, washed up on the river’s shore. I’ve seen oodles at Norrie Point and the ones in the photographs were in Beacon. In the shoreline photo below, look for the black pods among all the driftwood.
Betsy Blair, manager of the Hudson River National Estuarine Research Reserve, said the plants were released in a garden pond near Schenectady in the late 19th century.
“They gradually made their way into the Mohawk River and down to the Hudson, making their appearance in the late 1930s or so. They now occupy about 2% of the river’s surface area, although you might think it’s more when viewing some of the larger patches of bright green floating vegetation during the growing season,” she wrote in an e-mail.