Iris pseudacorus are very competitive against native plants due to their ability to form dense colonies and impenetrable thickets, ultimately displacing the native plants, and reducing habitat availability for animals as a result. Thriving in wetlands, their buoyant seeds are spread over long distances by water. All parts of the plant are poisonous to livestock and other animals. The rhizomes of the plants can survive harsh droughts, allowing for survival through dry conditions. The roots of the iris create a mat which compacts soil and prevents seed germination of native plants like cattails and native irises.