New Zealand Status: Introduced
Conservation Status: n/a
Myriophyllum aquaticum is an aquatic, perennial plant that grows submerged or emergent. Submerged leaves are 15-35mm long with 20-30 divisions per leaf while emergent leaves are 20-50mm long with 6-18 divisions per leaf. The blue-green emergent leaves are stiffer and darker coloured than the submersed leaves which are limp, often appearing to be decaying, but stems are very robust and form adventitious roots at the nodes. The flowers are white, inconspicuous, and form where emergent leaves attach to the stem.
M. aquaticum can rapidly colonise wetlands and forms dense mats that trap sediments, crowd out native vegetation. Light is strongly reduced and water flow impeded.
Myriophyllum aquaticum occurs in freshwater lakes, ponds and streams. It also grows on damp ground such as mud banks and in wetlands. It is classed as a pest species in several countries including NZ.
© Geografpix Photography, Steve Reader