Late afternoon daylight waned as I rounded the meander of the Sacandaga River that entered Duck Bay and paddled up to a gentle rapid. Turning my kayak around for my home voyage, I took a couple strokes and just about had a heart attack. There on the shore grew a small clump of gorgeous, yellow flowers. I instantly knew it was invasive yellow iris. A series of fortunate events shows how early detection / rapid response works to nip invasive species infestations in the bud.
A popular garden flower, yellow iris (Iris psuedacorus) was introduced from the Mediterranean and Europe to the United States as an ornamental. Without the checks and balances found on its home turf, it can reproduce rapidly to form monotypic stands that out-compete native vegetation. Invasive yellow iris can adversely impact fish habitat and bird nesting grounds, and impede water flow. Resins may result in skin irritation in humans who come into contact with the plant and vomiting in livestock that ingest it.
This beautiful perennial colonizes shallow waters, wetlands, shorelines, ditches, forest fringes, and stream banks. Yellow iris has invaded the Adirondacks. In Hamilton County I have spotted it planted in gardens on private property, but this was my first encounter in a riparian environment.
Its ability to thrive in harsh conditions including drought, low oxygen, acidic pH, and brackish waters gives yellow iris a competitive edge. Spread occurs by underground networks of horizontal roots called rhizomes that can shoot up hundreds of plants. Reproduction also occurs by seeds that stay afloat in water and move to new locations far from their parent plant.
Even though leaves are quiet similar to native blue flag iris and cattail, it is easy to spot invasive yellow iris in June when the plant produces showy flowers. Three droopy yellow sepals often display brown or purple mottling. Three erect, yellow petals point up above the sepals. The bloom period is short. I spotted the flowers on June 14 and a week later they were gone. Sword shaped leaves with a rib in the center grow in a fan. Plants reach 3 to 4 feet in height.
As a Conservation Educator for the Hamilton County Soil and Water Conservation District, I have had wonderful opportunities to learn management techniques for invasive plants through our partnership with the Adirondack Park Invasive Plant Program (APIPP). In 2005, 2007, and 2008, APIPP and our staff rallied together to prevent the spread of yellow iris. I saw first-hand just how dense and wide spread populations can become during management hikes in the Siamese Ponds Wilderness near Barton Mine in North River. We cut flowering heads and stems, and bagged all vegetation in an effort to slow the spread. APIPP’s certified herbicide applicators stem injected plants with a death elixir sensitive to wetland conditions.
Because of my job, I knew exactly what to do when I spotted the small cluster of yellow iris growing in Duck Bay. When I arrived at the Conservation District office for work, I logged onto the mapping website hamcomaps.net to determine who owned the land. District Manager Elizabeth Mangle called the property owner who graciously gave our staff permission to implement best management practices.
My co-worker Lenny Croote and I spent 10 minutes cutting and bagging all stems, leaves, and flower heads. A feeling of intense satisfaction came over me when the last few invasive iris plants were removed from the river bank. The site was documented in a GIS database and will be monitored annually to clear out any re-growth.
A total of 6 days passed from when the site was initially detected to when plants were removed. When invasive species are discovered early, there is the best opportunity for successful management.
Photos: Above, the author manages yellow iris in Duck Bay; middle and below, yellow iris.