Whorled water milfoil
Encyclopedia
The whorled water milfoil, Myriophyllum verticillatum is an invasive
aquatic plant
.
With the increase in water sports, the spread of many water milfoils (Haloragaceae) has increased over the years. The spread of a milfoil is not only within one area but, sometimes it spread from one area to another many miles away.
To the untrained eye the species of whorled water milfoil can all look similar to other species. Whorled water milfoil (Myriophyllum verticillatum) is a native to much of the United States, Alaska, and the United Kingdom. Whorled water milfoil closely resembles another native milfoil, called northern water milfoil
(M. sibiricum) Whorled water milfoil is also easily confused with four types of invasive milfoils: Eurasian water milfoil
(M. spicatum), Variable water-milfoil (M. heterophyllum), Parrot feather (M. aquaticum), and hybrid water milfoil (M. heterophyllum X M. laxum).
Another way to distinguish whorled water milfoil is to look for turions, winter buds that appear toward the end of its growing season. This milfoil is one of a few that produce turions. This characteristic can also rule out other types of water milfoil that lack turions such as Eurasian water milfoil, parrot feather, hybrid water milfoil, and low water milfoil. The turions of this milfoil look like long yellowish-green club-shaped buds with small stiff leaves attached to the submerged stem. In the spring after dormancy the small, thick, dark green turions expand and grow from the stem. As the plant develops roots and continues to grow, the larger green summer leaves are produced at the tip of the plant. Turion leaves can be seen at the base of the plant sometimes into July. In fall the turions, with some other plant material, often break away from the majority of the rooted plant and float to new areas. Those fragments can be found washing up along shorelines in late fall. The stems of the whorled water milfoil form into mats from branched and unbranched stems that grow to be 20 to 100 inches long.
s, such as some types of pondweed (Potamogeton strictifolius) and (Potamogeton ogdenii), water star-grass (Heteranthera dubia
) and water-marigold (Megalodonta beckii).
and are pollinated by wind.
It is also ideal in providing protection and respiration for fish spawn
Management of whorled water milfoil is not exactly know, but natural competition with other invasive aquatic plants
has been main control so far. There are a few management practices that some places are using, but they have not been approved for long-term usage.
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
aquatic plant
Aquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
.
With the increase in water sports, the spread of many water milfoils (Haloragaceae) has increased over the years. The spread of a milfoil is not only within one area but, sometimes it spread from one area to another many miles away.
To the untrained eye the species of whorled water milfoil can all look similar to other species. Whorled water milfoil (Myriophyllum verticillatum) is a native to much of the United States, Alaska, and the United Kingdom. Whorled water milfoil closely resembles another native milfoil, called northern water milfoil
Myriophyllum sibiricum
Myriophyllum sibiricum is a species of water milfoil known by the common name shortspike water milfoil. It is native to Russia, China, and much of North America, where it grows in aquatic habitat such as ponds and streams. It generally grows over a meter long, its green stem drying white. It is...
(M. sibiricum) Whorled water milfoil is also easily confused with four types of invasive milfoils: Eurasian water milfoil
Myriophyllum spicatum
Myriophyllum spicatum is a species of Myriophyllum native to Europe, Asia, and north Africa. It is a submerged aquatic plant, and grows in still or slow-moving water.-Description:...
(M. spicatum), Variable water-milfoil (M. heterophyllum), Parrot feather (M. aquaticum), and hybrid water milfoil (M. heterophyllum X M. laxum).
Description and identification
The best way to identify whorled water milfoil (M. verticillatum) is by looking at its two different types of leaves. The first type is the submersed leave, which looks feathery and contain about 5 to 14 leaflet pairs per leaf. (Bottom of Photo 3) The whorls along the stem contain about 4 to 5 leaves, which are spaced about 1 cm apart. The other type is known as the emergent leaves. These leaves occur on the emergent spike and are pinnately lobed. From June till September whorled water milfoil produces flowers and fruits above or at the water's surface on erect spikes along the emergent leaves. The emergent leaves are typically two or more times longer than the flowers and fruits.Another way to distinguish whorled water milfoil is to look for turions, winter buds that appear toward the end of its growing season. This milfoil is one of a few that produce turions. This characteristic can also rule out other types of water milfoil that lack turions such as Eurasian water milfoil, parrot feather, hybrid water milfoil, and low water milfoil. The turions of this milfoil look like long yellowish-green club-shaped buds with small stiff leaves attached to the submerged stem. In the spring after dormancy the small, thick, dark green turions expand and grow from the stem. As the plant develops roots and continues to grow, the larger green summer leaves are produced at the tip of the plant. Turion leaves can be seen at the base of the plant sometimes into July. In fall the turions, with some other plant material, often break away from the majority of the rooted plant and float to new areas. Those fragments can be found washing up along shorelines in late fall. The stems of the whorled water milfoil form into mats from branched and unbranched stems that grow to be 20 to 100 inches long.
Habitat
Most whorled water milfoil occurs in semi-shallow ponds, lakes, marshes, ditches and slow running streams of lowland districts Milfoil thrives in areas with a light sandy bottom and medium loamy soils. Overall, the plant grows best in still waters with lkali soil|alkaline soils. Whorled water milfoil is sometimes found with or near other aquatic plantAquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
s, such as some types of pondweed (Potamogeton strictifolius) and (Potamogeton ogdenii), water star-grass (Heteranthera dubia
Heteranthera dubia
Heteranthera dubia is a species of aquatic plant known by the common names water stargrass and grassleaf mudplantain. It is native to North and Central America where it is widespread from Canada to Guatemala. It lives submersed in freshwater such as rivers and lakes. It is quite variable in...
) and water-marigold (Megalodonta beckii).
Distribution
Native in North America, Alaska, British Columbia, United Kingdom, Asia, N. Africa, and invasive to Ireland.Propagation and reproduction
Whorled water-milfoil reproduces by producing turions between September and November each year. These over-wintering turions sink to the bottom of the floor where they remain dormant until February [Caffrey,2006]. These fragments will give rise to numerous small thin roots that bed into soil to start growing in spring. The plants are monoecious (individual flowers are either male or female, but both sexes can be found on the same plant)and are pollinated by wind.
Control and uses
Whorled water milfoil is a good water oxygenator in small quantities such as fish and frog ponds.It is also ideal in providing protection and respiration for fish spawn
Management of whorled water milfoil is not exactly know, but natural competition with other invasive aquatic plants
has been main control so far. There are a few management practices that some places are using, but they have not been approved for long-term usage.
External links
- Comb Water-Milfoil, Myriophyllum verticillatum, Massachusetts Division of fisheries & Wildlife, viewed on May 2009
- Maine Field Guide to Invasive Aquatic Plants, Whorled water-milfoil, March 2009
- Plants For A Future, Myriophyllum verticillatum, viewed on March 2009
- USGS, Western Wetland Flora: Whorled water-milfoil, viewed on March 2009
- Whorled Leaf Water Milfoil, viewed on March 2009
- Wisconsin Department of Natural resources, Native Water-milfoils, viewed on March 2009