Myriophyllum spicatum

Eurasian watermilfoil was accidentally introduced from Eurasia in the 1940s. Two theories exist as to how it entered North America: (1) it escaped from an aquarium, or (2) it was brought in attached to commercial or private boats. A resort owner is thought to have introduced watermilfoil into the Tennessee Valley Authority reservoir system in 1953.

Introduced accidentally from Eurasia in the 1940s, Eurasian water-milfoil possibly escaped from an aquarium or was brought in on a commercial or private boat.

This submerged aquatic plant is a perennial that develops stems up to 9' long. The stems branch sparingly below and abundantly above; the upper stems often extend parallel to the surface of the water. Individual stems are light green, pale red, pale reddish green, or nearly white; they are terete, slightly succulent, and glabrous. Along these stems, there are whorls of 4 leaves (rarely 3 or 5) that are medium to dark green and glabrous. The internodes (spatial separation along the stem) of the whorled leaves are about ¾-2" in length. Individual leaves are ¾-1½" long and a little less across; they are deeply pinnatifid, each leaf dividing into 10-20 filiform (worm-like) lobes on each side. This provides the leaves with a feathery appearance. The upper stems terminate in floral spikes about 2-8" long. These spikes are usually exerted above the water surface. The central stalks of these spikes resemble the stems, except they are slightly more narrow. Each spike produces sessile unisexual flowers (rarely perfect) that are arranged in whorls of 4; the male flowers are located above, while the female flowers are located below. These whorled flowers are widely separated from each other along each spike. Each male flower is about 3 mm. long, consisting of 4 pink petals and 8 stamens; the petals are early-deciduous. Each female flower is about 2-3 mm. long, consisting of a 4-lobed pistil with feathery stigmata; petals are insignificant or absent. Underneath each male flower, there is a green bractlet that is oblong-lanceolate or oblanceolate in shape. Underneath each female flower, there is a green bractlet that is oval in shape. These bractlets are about the same length or a little shorter than the flowers. The blooming period usually occurs from early summer to early fall. If the weather and water are warm, individual plants may bloom more than one time per year. The flowers are cross-pollinated by wind. Afterwards, the floral spikes start to sag into the water as the fruits of the female flowers develop. Each fruit is 2 mm. long and globoid-ovoid in shape with 4 lateral lobes; these lobes are smooth, except along their margins, where they may be slightly warty. Each fruit divides into 4 chunky 3-sided seeds. The root system is shallow and fibrous. This plant can reproduce vegetatively as its fragile stems often divide, forming plant fragments that drift in the water. If the stems of these plant fragments become lodged in the substrate of the water body, they can develop new roots. Winter turions (dense buds of cold-adapted leaves) are not developed; instead this plant dies down to its root crown for the winter.

spicatum: spicate

The non-native Eurasian Water Milfoil is occasional in northern and central Illinois, while in the southern section of the state it is uncommon. However, this invasive plant is still expanding its range in Illinois and it will undoubtedly become more common in the future. Distribution records from herbariums probably underestimate its abundance within the state. Eurasian Water Milfoil was introduced into North America from Eurasia; it also occurs in parts of Africa. The earliest records of this plant in Illinois are dated 1916, when it was found in Lake County. Habitats include lakes, ponds, reservoirs, drainage canals, and streams with slow currents. By displacing native aquatic plants, Eurasian Water Milfoil can become the dominant aquatic plant in a body of water. Generally, young human-created bodies of water are preferred habitats as there is little build-up of organic matter to acidify the water and there is little shade from neighboring trees and shrubs.

Gulf of Mexico, Polish Exclusive Economic Zone, Swedish Exclusive Economic Zone

Watermilfoil occurs in thirty-three states east of the Mississippi River and has recently been found in Colorado. It is abundant in the Chesapeake Bay, the tidal Potomac River, and several Tennessee Valley reservoirs.

Eurasia and Africa 

Eurasian water-milfoil occurs in at least 33 states east of the Mississippi River and has recently been found in Colorado. It is abundant in the Chesapeake Bay, the tidal Potomac River and several Tennessee Valley reservoirs. Typical habitat includes fresh to brackish water of ponds, lakes, slow-moving streams, reservoirs, estuaries and canals. It is tolerant of many water pollutants.

Eurasia and Africa

Nile region and eastern desert.

Mediterranean region, Europe, Asia, south Africa, north and south America.

Myriophyllum spicatum L.:
China (Asia)
Mexico (Mesoamerica)
United States (North America)
South Africa (Africa & Madagascar)
Canada (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Distribution: Found throughout Europe, Asia, N. & S. America, N. & S. Africa.

Europe, Africa, W. & C. Asia, Himalaya, Siberia, India, east to China and Japan, Alaska, S. America (possibly introduced).

Eurasian watermilfoil, also called spike watermilfoil, is an emergent, herbaceous aquatic plant. Stems grow to the water surface, usually extending 3 to 10, but as much as 33, feet in length and frequently forming dense mats. Stems of Eurasian milfoil are long, slender, branching, hairless, and become leafless toward the base. New plants may emerge from each node (joint) on a stem, and root upon contact with mud. The grayish-green leaves of Eurasian watermilfoil are finely divided and occur in whorls of three or four along the stem, with 12-16 pairs of fine, thin leaflets about 1/2 inch long. These leaflets give milfoil a feathery appearance that is a distinguishing feature of the plant. Eurasian watermilfoil produces small yellow, 4-parted flowers on a spike that projects 2-4 inches above the water surface. The fruit is a hard, segmented capsule containing four seeds.

• Plant: herbaceous aquatic plant; stems grow to the water surface, usually extending 3-10 ft. but as much as 33 ft. in length and frequently forming dense mats; stems are long, slender, branching, hairless and become leafless toward the base; new plants may emerge from each node (joint) on a stem and root upon contact with mud.
• Leaves: bright green, finely divided and occurring in whorls of three or four along the stem, with 12-16 pairs of fine, thin leaflets about ½ in. long that give it a feathery appearance.
• Flowers, fruits and seeds: produces small, yellow, four-parted flowers on a spike that projects 2-4 in. above the water surface; flower spikes often remain above water until pollination is complete; fruit is a hard, segmented capsule containing four seeds.
• Spreads: vegetatively by rhizomes, fragmented stems and axillary buds that develop throughout the year. Although seeds are usually viable, they are not an important means of dispersal.
• Look-alikes: many species of submerged aquatic plants including non-native invasive parrot-feather (Myriophyllum aquaticum), and native species such as Northern water-milfoil (M. sibiricum), coontail (Ceratophyllum dmersum) and water marigold (Megalodonta beckii).

Plants mostly monoecious, rarely with bisexual flowers. Stem much branched, 100-250 cm, densely leafy in upper part, sparsely light green warty; internodes ca. 3 cm. Submerged leaves 4- or 5-whorled, pectinate, broadly ovate in outline, 3-3.5 × 1-2.5 cm; segments in 13-16 pairs, filiform, 1-1.5 cm. Inflorescence a terminal spike of 4-whorled flowers, 6-10 cm; bracts reniform or suborbicular, shorter than flowers, broader than long. Male flowers: bracteoles rhombic to elongate, margin entire; calyx broadly campanulate, 0.5-1 mm, 4-parted nearly to middle; petals 4(or 5), pale pink, elliptic, 1.5-2.5 mm; stamens 8, without androphore. Female flowers: bracteoles pectinate, lanceolate in outline; calyx tubiform, 0.7-1 mm, margin shortly lobed; petals absent or minute and caducous. Fruit 4-loculed, subcylindric, ca. 2 × 1.5 mm; mericarps abaxially rounded, smooth or sparsely verrucose along margins. Fl. and fr. Apr-Sep.

Submerged perennial. Stems thick, 30-150 cm long, branched, glabrous, rhizome rooting. Leaves 10-25 mm long, pectinate, with 20-26 segments. Spikes terminal, 50-70 mm long, with flowers in whorls of 4 in the axils of bracts; the upper flowers male, the lower female. Bracts 1.5-3 mm long, the upper obovate, entire; the lower: pinnatifid or with a deeply cleft margin. Male flower : sepals 0.5-1 mm long, triangular, obtuse; petals 2 mm long, oblong, cucullate, reddish. Stamens 8, filaments short; anthers 1-1.5 mm long. Female flower: calyx c. 1.5 mm long; petals minute. Ovary c. 1.5 mm long, subglobose; styles short, stigmas plumose. Fruit 2 mm long, subglobose.

3000 m

The non-native Eurasian Water Milfoil is occasional in northern and central Illinois, while in the southern section of the state it is uncommon. However, this invasive plant is still expanding its range in Illinois and it will undoubtedly become more common in the future. Distribution records from herbariums probably underestimate its abundance within the state. Eurasian Water Milfoil was introduced into North America from Eurasia; it also occurs in parts of Africa. The earliest records of this plant in Illinois are dated 1916, when it was found in Lake County. Habitats include lakes, ponds, reservoirs, drainage canals, and streams with slow currents. By displacing native aquatic plants, Eurasian Water Milfoil can become the dominant aquatic plant in a body of water. Generally, young human-created bodies of water are preferred habitats as there is little build-up of organic matter to acidify the water and there is little shade from neighboring trees and shrubs.

Typical habitat for Eurasian watermilfoil includes fresh to brackish water of fish ponds, lakes, slow-moving streams, reservoirs, estuaries, and canals.. It is tolerant of many water pollutants. Eurasian watermilfoil tends to invade disturbed areas where native plants cannot adapt to the alteration. It does not spread rapidly into undisturbed areas where native plants are well established. By altering waterways, humans have created a new and unnatural niche where milfoil thrives.

Depth range based on 4 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 2 - 2
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Stagnant waters, lakes, ditches, slow streams, springs; near sea level to 4200 m, rarely to 5200 m in springs in Xizang. Throughout China [Asia, Europe].

One possible biocontrol agent is the Water Milfoil Weevil (Euhrychiopsis lecontei). This weevil is native to the American Midwest and it is known to feed on Eurasian Water Milfoil. However, it will also feed on native water milfoil species (Myriophyllum spp.). Pond Snails (Lymnaea spp.) and Wheel Snails (Planorbis spp.) also feed on these plants. Some vertebrate animals feed on water milfoil species. According to Pearse (1918), 2-5% of the food of three fishes consisted of water milfoil in Wisconsin; these fish species are Lepomis gibbosus (Pumpkinseed), Noturus gyrinus (Tadpole Cat), and Perca flavescens (Yellow Perch). Several turtles also feed on these aquatic plants, including Chelydra serpentina (Snapping Turtle), Chrysemys picta (Painted Turtle), Emys blandingii (Blanding's Turtle), and Trachemys scripta (Slider); see Lagler (1943) and Ernst et al. (1994). Several wetland birds eat the foliage and/or seeds of water milfoil. They include such species as Cygnus buccinator (Trumpter Swan), Anas discors (Blue-Winged Teal), Anas platyrhynchos (Mallard), Aythya affinis (Lesser Scaup), Aythya valisineria (Canvasback), Oxynura jamaicensis (Ruddy Duck), Limnodromus griseus (Short-Billed Dowitcher), Calidris melanotos (Pectoral Sandpiper), and Calidris himantopus (Stilt Sandpiper); see Martin et al. (1951/1961) and Havera (1999). The foliage is a minor source of food for muskrats (Hamerstrom & Blake, 1939). Eurasian Water Milfoil can be spread through human-related activities. This aquatic plant can cling to boat hulls, propellers, anchors, boat trailers, and fish nets, from which it can escape into previously unoccupied lakes and rivers. Because this plant is sometimes cultivated in aquariums, it can spread into waterways when the contents of aquariums are dumped by their owners.

Fl. Per. May-July.

Most regeneration of Eurasian watermilfoil is from rhizomes, fragmented stems, and axillary buds that develop throughout the year. Flower spikes often remain above water until pollination is complete, then resubmerge. Although seeds are usually viable, they are not an important means of dispersal.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 7
Specimens with Barcodes: 8
Species With Barcodes: 1

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Rounded Global Status Rank: GNR - Not Yet Ranked

Large harvesting equipment can be used to mechanically remove Eurasian water-milfoil in larger areas; a sturdy hand-rake can be used for smaller areas. Other options include manipulation of water level, use of water colorants or floating aquatic plants to reduce light penetration, physical barriers and chemical control. Potential impacts to existing native aquatic plant species should be evaluated carefully before using any of these techniques.

The preference is full sun, clear alkaline water up to 8' deep, and a substrate containing clay or other fine inorganic material. However, Eurasia Water Milfoil will adapt to more acidic water and substrates containing sand, silt, or gravel. This plant can spread aggressively and it should not be planted in North America.

Eurasian milfoil can form large, floating mats of vegetation on the surface of lakes, rivers, and other water bodies, preventing light penetration for native aquatic plants and impeding water traffic. The plant thrives in areas that have been subjected to various kinds of natural and manmade disturbance.

Water-milfoil tends to invade disturbed areas and does not typically spread into undisturbed areas where native plants are well established. It can form large, floating mats of vegetation on the surface of lakes, rivers and other water bodies, that impede water traffic and reduce light for native aquatic species. It thrives in areas that have been subjected to natural and man-made disturbance.