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The Mission of the Yellowstone County Weed Department is to assist the public, private, and other government agencies to manage and control existing noxious weed infestations as well as to prevent new invasive species from infesting Yellowstone County.
Eurasian WatermilfoilMyriophyllum spicatum
Photo from Weeds of the West, revised edition.
Photos from Montana Weed Control Association
| Attribute | Description |
|---|---|
| Growth Habit | Submerged herbaceous perennial herb native to Europe, Asia, and northern Africa. Accidentally introduced to the United States in the late 1800’s. |
| Leaves | Three to four bright green leaves are whorled around the stem at each joint. Each leaf is 1.2 inches in length and has 12 to 48 thread-like divisions. Leaves rarely extend above the water surface. |
| Stem | Stems can be 10 feet or more in length and 0.1 inches thick. |
| Flower | A rigid pink flowering spike, from 2 to 8 inches long, is held erect above the water surface from June to August. Small yellow four-petaled flowers are arranged in clusters on the flowering spike. |
| Roots | Eurasian Water Milfoil has numerous roots at the base of the plant and along the stem. |
| Seeds | Hard, segmented capsule containing four seeds. |
| Reproduction | Asexual reproduction via sprouting plant fragments and rhizomes is the dominant means of spread. |
| Habitat | Lakes, ponds, slow-moving streams, reservoirs, estuaries, and canals. |
| Biological Control | — |
| Herbicides | Sonar AS. |