Diggings logo

WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on local landscape and natural history of Pend Oreille County, Washington. A partnership with the Kalispel Tribe of Indians Natural Resources Department has allowed us to expand this program through EPA funding to include more classes, a newsletter and this website.

Worse than Milfoil?


by Sharon Sorby

It may be hard to believe, but there are worse aquatic weeds than Eurasian watermilfoil. The three candidates on my list include hydrilla, Brazillian elodea and parrotfeather milfoil.

Although hydrilla is neither an attractive plant nor sold as a pond or aquarium aerator, it could arrive as a contaminate of packing material for other aquatic plants ordered from nurseries specializing in aquatic plants. It resembles our native elodea, but in cross section it has 5 leaves instead of the four our native elodea has and there are serrations along the leaf edges giving it a rough feeling when drawn through the fingers. If you should discover it, please notify the Weed Board and dispose of it where it cannot get into water.

Hydrilla is worse than milfoil because it is very difficult to control. It produces a hard reproductive structure called a turion that settles into the sediment and it cannot be controlled. It may sit there, undetected, for several years before sprouting and the new infestation could grow quite large before it is found.

Brazillian elodea, also called anacharis in the aquarium trade, is sold as an aerator. It also resembles our native elodea; however it is much larger. It is worse than milfoil as it is resistant to the herbicides available for treating it and will come-up around a barrier mat placed to smother aquatic weeds. Please make sure this one does not find its way to natural waters.

Parrotfeather milfoil is an attractive plant, often used as an ornamental or aerating aquatic plant -- both for ponds and aquaria. It is worse than milfoil because the top sticks up out of the water forming a dense mat that shades out plants below (including itself). This makes injecting herbicides below ineffective. The leaves above the water have a hard coat that makes penetration with herbicides very difficult.

Please keep in mind, all three of these are illegal to import, buy, sell or otherwise allow to grow in Washington State. There are a couple of other honorable mentions, yellow water iris and water hyacinth. Neither of these should be planted nor allowed to escape into natural waters of the County.

<----previous article...Diggings Dec 2006...next article---->