Eurasian
Water Milfoil
(Myriophyllum spicatum)
Three to four
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Eurasian water milfoil is a submerged herbaceous perennial herb native to Europe, Asia, and northern Africa. It was accidentally introduced to the United States in the late 1800s, probably as an escaped aquarium species or from a boat. Eurasian water milfoil has numerous roots at the base of the plant and along the length of the stem. Stems can be 10 feet or more in length and 0.1 inch thick. Stems grow to the water surface, where they branch and form dense floating mats of vegetation. The long, slender hairless stems are leafless toward the base and whitish when dry. Three to four bright green leaves are whorled around the stem at each joint. Each leaf is 1.2 inches long and has 12 to 48 thread-like divisions. (The Latin name, Myriophyllum, meaning many-leaved, refers to these finely dissected feather-like leaves.) Leaves rarely extend above the water surface and become matted when they are removed from water. A rigid pink flowering-spike, form 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. The fruit is a hard, segmented capsule containing four seeds. Seeds are not an important means of spread. Asexual reproduction via sprouting plant fragments and rhizomes is the dominant means of spread. |
