Curly-leaf pondweed is a non-native aquatic plant that can tolerate low temperature waters like those in its native region of northern Europe and Asia. It has proven to be a strong competitor with native species in Wisconsin lakes and streams, particularly in the spring and early summer when it gets a head start on the local competition. The first confirmed specimen of curly-leaf pondweed in the United States was collected in Delaware in the mid 1800's. By the turn of the century, it had spread along the East Coast from Virginia to Canada, and by the 1930's it was established in the Midwest. Currently, curly-leaf pondweed is found throughout the lower 48 states.

Description: This submersed aquatic plant has spaghetti-like stems that often reach the lake surface by mid- June. The oblong leaves attach directly to the stem in an alternate pattern. Leaf margins are wavy (resembling lasagna noodles) and finely toothed creating an overall leaf-texture that is "crispy." In spring, curly-leaf produces flower spikes that stick up above the water surface. The small flowers are arranged in a dense terminal spike  on a curved 1-2 inch (25-50 mm) stalk. By June, nutlets (achenes) are mature on the stalks and may drop to the sediment. These seeds playa relatively small role in reproduction compared to their vegetative winter buds or turions. Turions look like small brown pinecones and are produced in great numbers by mid-summer on shortened branchlets along the stem. Studies of curly-leaf beds in lakes have shown as many as 1600 turions in a one square yard (.8 m) plot. The germination rate for these turions is high, ranging from 60 to 80.

Habitat: Curly-leaf is considered a deep-water plant. However, in a lake where it is dominant, a bed of curly-leaf may start in 1-2 feet (30-60 crn) of water and extend out to depths of 10-12 feet (3-4 m) or more. This plant has a competitive advantage over many native species because it can tolerate low light conditions, both in the summer during algal blooms and during winter under ice and snow cover. It has been found growing beneath 20 inches (50 cm) of ice and a heavy blanket of snow. The cool water adaptations of curly-leaf set it apart from other Wisconsin aquatic plants. It is actively growing under the ice while most plants are dormant, but dies back in mid-July when other aquatic plants are just reaching their peak growth for the year. In lakes where curly-leaf is dominant, the summer die-off causes increased nutrient levels that can lead to habitat disturbance and degraded water quality (algal blooms).

Management and Control: Curly-leaf pondweed provides food for ducks and valuable winter and spring
habitat for fish and invertebrates. These values are overshadowed when curly-leaf dominates a plant population
because summer die-off leaves little habitat for the rest of the season and causes increased nutrient levels leading
to algal blooms. Selective control of curly-leaf stands and protection or restoration of native species can lead to
a balanced plant population. Protecting water quality will also help keep curly-leaf in check because it has a
competitive advantage over native plants when water clarity is reduced.

EURASIAN WATER-MILFOIL
Myriophyllum spicatum

Eurasian water-milfoil is an exotic species introduced to the United States from its native range in Europe and Asia. The fast growing shoots and extensive canopy formation can obstruct recreation and navigation. The ability to grow in cool water gives it a quick start in the spring. Eurasian water-milfoil often crowds and shades native plants, giving it a competitive advantage.

Description: Eurasian water-milfoil has long, spaghetti like stems, sometimes 6.6 feet (2 m) or more in length, that emerge from roots and rhizomes. Leaves are divided like a feather, with a short stalk and about 12-20 pairs of thread-like leaflets. The leaf divisions are all about the same length and closely spaced, resembling the bones on a fish spine. Leaves are in whorls of 3-5, and can be widely spaced 0.4 - 1.2 inches (1-3 crn) or more. The flower spike sticks out of the water with whorls of flowers in the axils of short bracts. The 0.08-0.12 inch (2-3 mm) fruit has four parts with a smooth to slightly roughened surface.

Habitat: Eurasian water-milfoil grows submersed in water depths of 3-20 feet (0.9-6 m). The only parts of the plant that may grow out of the water are the flower stalks, which are only a few inches tall. However, the submersed shoots may form a dense canopy right at the water's surface, causing the infamous nuisance problem as well as impacting native plant and animal communities. Rooted in the bottom, the root crowns have many stems growing from them up to the surface. Near the surface, each stem may branch multiple times to form a dense mass.

Similar species: There are seven native species of water-milfoil in this region. Eurasian water-milfoil most closely resembles northern water-milfoil (Myriophyllum sibiricum). The most reliable way to distinguish between them is by the number of leaf divisions. Eurasian water-milfoil usually has more than 12 pairs of leaflets, whereas Northern water-milfoil has less than 12 (usually 5-12). The presence or absence of winter buds in late summer is also a helpful characteristic. Northern water-milfoil produces winter buds, but Eurasian water-milfoil does not. Although individual plants of these two species may look similar, their growth form is quite different. Northern water-milfoil doesn't typically form a branched canopy at the water's surface and it grows in a more controlled manner with slower growth and less fragmentation.

Management and Control: Eurasian water-milfoil has been the target of many management strategies ranging from mechanical harvesting to herbicides. There has recently been some evidence that a native weevil (Euhrychiopsis lecontei) may provide a biological control. This tiny aquatic weevil has been associated with some natural declines of Eurasian water-milfoil. In some test plots on milfoil infested lakes, the weevil has been shown  to reduce milfoil growth and limit canopy formation. The possibility of using a native weevil for biocontrol shows promise (Sheldon and Creed 1995).

PURPLE LOOSESTRIFE
Lythrum salicaria & Lythrum virgatum

Purple loosestrife is native to Europe and Asia where insects and diseases native to that area have kept it in check. It was introduced to North America as a garden plant but has since spread to wild areas and depleted natural habitat for native plants and animals. Cultivars of loosestrife are still sold as garden plants in some parts of the U.S. However, Wisconsin law bans the sale, distribution, planting or cultivation of non-native purple loosestrife. Some plant producers claim to have sterile varieties of purple loosestrife. It appears that cultivars are capable of producing seeds if they cross-pollinate with another loosestrife plant.

Description: Purple loosestrife has angled 20-59 inch (50-150 em) tall stems that emerge from a woody rootstock. Lance-shaped 1-4 inch (3-lO cm,) long leaves attach directly to the stem, and often have fine hairs on their surface. The leaves may be opposite, in whorls of three, or spiraled around the stem. This seems to be related to the number of sides on a stem: four-sided stems have opposite leaves, five-sided stems have leaves in a spiral arrangement, and six-sided stems have leaves in whorls. All three stem types can be found on a single loosestrife plant. Clusters of magenta flowers are produced in leafaxils on a terminal spike. Each flower has 5-7 narrow petals 0.3-0.5 inches (7-12 mm) long that are wrinkled with a tissue paper consistency. The seeds produced are tiny but great in number. Mature loosestrife plants yield up to 2.7 million seeds per year that have the ability to remain viable in the soil for years before germination.

Habitat: Purple loosestrife can be found in a wide variety of sites from moist soil to shallow water and specifically near or in marshes, wetlands, streams, rivers, or lakes. Disturbed sites, along highways for example, also create an opening for germination of seeds and expansion of new colonies. Loosestrife can overtake a natural habitat and literally choke out the native vegetation, including rare or endangered plants. In addition, the wildlife that depend on the native vegetation for food or shelter are forced out of the area because loosestrife provides little food or habitat for native wildlife species.

Similar Species: There are several species of native flowering plants that are often mistaken for purple loosestrife so it is important to correctly identify the plant in question before taking steps toward control. Native plants that are commonly mistaken for purple loosestrife include blazing-star/gayfeather (Liatris pycnostachya), fireweed (Epilobium angustifolium), blue vervain (Verbena hastata), winged loosestrife (Lythrum alatum), and swamp loosestrife (Decodon verticillatus).

Management and Control: Purple loosestrife can be controlled using mechanical, chemical, and biological means. The best treatment plan depends mainly on the size and density of the infested site. Small to medium, 0.1-2 acres (0.04-0.8 hectare) sites with low to medium density of loosestrife plants (1 - 60) are best managed using mechanical and selective chemical treatments. Herbicides kill all plants, so careful application is necessary and a permit is needed from the Wisconsin DNR before applying herbicides in or near waterbodies. Permit fees are waived for controlling purple loosestrife. Large sites with high density of loosestrife are best managed through means of biological control using Galerucella sp. beetles available through the WDNR.