Parrot Feather (Myriophyllum aquaticum): A Non-Native Aquatic Plant in New Jersey Waterways
A member of the water-milfoil family Halogragaceae, Parrot feather is a perennial rooted aquatic plant that has both a submersed and an emergent form which can extend up to 30 cm (12 in) above the water surface. Submerged leaves are often decayed or limp with a more reddish appearance and are 1.5–3. 5 cm (0.5–1.5 in) long, with 10–15 leaflet pairs per leaf. Sturdy, sparsely branched stems grow up to 2 m long and 5 mm in diameter. When shoots reach the water surface, plant growth changes to a horizontal pattern with extensive lateral branching followed by vertical stem growth (Fig. 1). Emergent leaves are stiff, bright green to bluish green, 2–5 cm long arranged in whorls of 3–6 leaves around the stem (Fig. 2). The leaves themselves are divided into 12–35 leaflet pairs giving them a featherlike appearance (Fig. 3). They sprawl along the water surface or wet soil and can rise up above the water and look almost like small fir trees up to 30 cm (1 ft) tall. Tiny 0.5 mm, four sepal white flowers are produced on short stalks at the base of emergent leaves. In South America, male and female flowers are on separate plants, but in North America only female plants are produced. Plants spread by rhizomes and growth from plant fragments. Adventitious roots emerge from the stem nodes allowing the plants to grow vegetatively.