The iris shares its name with the Greek goddess of the rainbow, ostensibly for the multitude of colors found across its hundreds of species worldwide. In this neck of the woods, though, they present only in primaries: the blues of I. versicolor and I. prismatica, both locals, and the yellow Iris pseudoacorus, a Eurasian garden escapee that displaces native shoreline vegetation. The yellow flag iris invades both fresh and brackish ponds and marshes, forming dense colonies by rhizomes where nothing else can grow. If left unchecked, seeds and rhizome fragments will float downstream to form new stands. Pictured here is a pond next to Shank Painter Road in Provincetown, where Iris pseudoacorus has colonized opposite shores.
