Eurasian watermilfoil

Eurasian watermilfoil Myriophyllum spicatum Watermilfoil family
Key identifying traits Under water foliage usually found in whorls of 4 around the stem; no above surface leaves Each mature leaf has 12 or more pairs of leaflets; native milfoil has less than 12 Leaves appear feather-like or like fine herring bones and tend to collapse around stem if removed from the water unlike courser native milfoil that retains it’s shape out of water Small flowers are borne on leafless, reddish spikes that stand a few inches above the water and submerge after pollination Rooted plants will grow in water as deep as 25-30 feet depending on water clarity Biology and ecology A perennial plant that does produce seeds but that spreads almost entirely from fragments; plants naturally fragment in late summer & fall Fragments are also caused by and transported from place to place by watercraft and trailers Dense mats can form making boating, fishing and swimming impossible and displacing native plants Once commonly sold as an aquarium plant but now one of the most problematic plants in Washington Control Prevention – Learn to identify plants; know your waterbodies; beware of and check for plant fragments transported on watercraft and trailers Biological – Sterile grass carp or milfoil weevil may have very specific and limited application Cultural – Healthy native plant communities help reduce likelihood of establishment but don’t stop it Mechanical – Harvesting, rotovation, pulling, dredging and bottom barriers all have their uses Chemical – Some effective at label rates but can only be used with required permits and licenses; refer to the PNW Weed Management Handbook for specific chemical recommendations and the Department of Ecology site for more information about the weed, permits and control options	Flowering stem
	Milfoil "whorl"
	Eurasian milfoil on left; coarser, Northern (native) milfoil on right
	Dangerous mats formed by Eurasian milfoil
*Where found –* Found in several Stevens County lakes and rivers and in many nearby counties as well. Statewide spread has been dramatic since first found near Seattle in 1965. MSdoc pdf