Mermaidweed is a small, native emersed plant – a member of the watermilfoil family. It is usually found in the water but often becomes stranded above the water where it grows quite well. It flowers in the spring and early summer. The whitish to green stems are often sprawling; the upper parts are often erect. Unlike other watermilfoils, mermaidweed leaves are alternate on the stem. They are feathery. Flowers are tiny and greenish white. Fruits are three-angled nutlets that are attached at the leaf axils. They are conspicuous. Mermaidweed is the only small aquatic plant to have such three-angled nutlets. Mermaidweed may sometimes be confused with parrotfeather (Myrophyllum aquaticum). Mermaidweed leaf arrangement is single and alternate on the stem, while parrotfeather leaves (6-8) are arranged in whorls about the stem.