|Yellow Iris at Allegany State Park in NY (Red House Lake in the background) during the Allegany Nature Pilgrimage -- © Dave Spier|
Yellow Iris -- © Dave Spier
Yellow Iris, also called "water flag," grows in the shallow edges of wetlands and ponds where the depth is generally less than 10 inches. It has spread across the United States and you can find a distribution map on the USGS website. Since I live in the Finger Lakes region of New York and travel Route 31, I mostly notice it along sections of the old Erie Canal on my way to the Montezuma Audubon Center.
The scientific name, Iris pseudacorus, comes from Iris, the Greek goddess of the rainbow (referring to the many colors in this family of plants) plus a contraction of the Greek words for "false sweetflag," referring to the similar, sword-like leaves, although sweetflag is actually an arum related to Jack-in-the-pulpit and Skunk-cabbage. Both the iris and the Sweetflag have long-pointed leaves with a prominent mid-rib.
The showy, yellow blossoms - up to four inches across - have three falling sepals surrounding three erect petals. The flowers are held above the leaves by stalks reaching a height of three to four feet. This made the species attractive to horticulturists who brought the plant to the United States in the early 1900's from its native European and North African habitats.
In suitable climates (generally the Southern Sates) it can be used to treat sewage and remove metals from wastewater. Given time this long-lived perennial can form dense, single-plant (monotypic) stands to the detriment of our native wetland plant species. It spreads by using underground rhizomes as well as seeds. Even though associated with wetlands, it can survive a drought up to three months and the seeds can survive a fast wildfire.
Be careful when handling this plant; it's poisonous and can cause skin irritation.
|Yellow Iris and leaves at Allegany State Park in NY during the Allegany Nature Pilgrimage -- © Dave Spier|
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