| Myriophyllum | |
|---|---|
| Myriophyllum aquaticum | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Saxifragales |
| Family: | Haloragaceae |
| Genus: | Myriophyllum |
| Species | |
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Myriophyllum (watermilfoil) is a genus of about 69 species of freshwater aquatic plants, with a cosmopolitan distribution. The center of diversity for Myriophyllum is Australia with 43 recognized species (37 endemic).[1] [2] Its name comes from Latin, "myrio" meaning "too many to count", and "phyllum", meaning "leaf".
These submersed aquatic plants are perhaps most commonly recognized for having elongate stems with air canals and whorled leaves that are finely, pinnately divided, but there are many exceptions. For example, the North American species M. tenellum has alternately arranged scale like leaves, while many Australian species have small alternate or opposite leaves that lack dissection. The plants are usually heterophyllous, leaves above the water are often stiffer and smaller than the submerged leaves on the same plant and can lack dissection. Plants are monoecious or dioecious, the flowers are small, 4(2)-parted and usually borne in emergent leaf axils. The 'female' flowers usually lack petals. The fruit is a schizocarp that splits into four (two) nutlets at maturity. [3] [4]
The fruits and leaves can be an important food source for waterfowl, which are thought to be an important source of seed and clonal dispersal.
This plant may be a hidden resource, eventually seen as a valuable cellulose feed stock in a biofuel refinery. Cellulosic ethanol, or butanol fuel are seen by many as growing trends in green fuels (including jet fuel).
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Three species (M. aquaticum, M. heterophyllum and M. spicatum) have become particular aggressive invasive plants of lakes, natural waterways and irrigation canals in North America. This has prompted the implementation of control plans by many U.S. states most affected by the invasions.
The widespread invasive, Eurasian water milfoil, is often controlled with herbicide containing the chemical diquat dibromide. Control can also be done through careful mechanical management, such as with Lake Mowers,[5] but caution must be used since this is a fragmenting plant, and the fragments may grow back.
Mechanical management can include the use of a long reach lake rake or aquatic weed razor blade tool. Using these tools would be similar to lawn work. These tools are most effective before seeds set. Another very effective use is to keep the plants from ever starting to grow through the use of a Weed Roller or a LakeMaid. These are considered to be automated and unattended machines. Permits may be required by various states. A guide to state permits and aquatic vegetation management can be found at http://www.invasivespeciesinfo.gov/
Recently, Professor Sallie Sheldon of Middlebury College has found that an aquatic weevil (Euhrychiopsis lecontei), which eats nothing but milfoil, may be the most effective weapon against it. [1]
Since roughly 2000, hand-harvesting of invasive milfoils has shown much success as a management technique. Several organizations in the New England states have undertaken large scale, lake-wide hand-harvesting management programs with extremely successful results. Acknowledgment had to be made that it is impossible to completely eradicate the species once it is established. As a result, maintenance must be done once an infestation has been reduced to afford-ably controlled levels. Well trained divers with proper techniques have been able to effectively control and then maintain many lakes, especially in the Adirondack Park in Northern New York where chemicals, mechanical harvesters, and other disruptive and largely unsuccessful management techniques are banned. The Adirondack Watershed Institute (AWI) of Paul Smiths College is one organization whose research has shown time and again the effectiveness of hand-harvesting techniques.