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Troublesome weeds seen choking area ponds

Fanwort

Fanwort.

Troublesome weeds choking area ponds include Eurasian milfoil, fanwort, hydrilla, water chestnut, and phragmites.

Eurasian milfoil

(Myriophyllum spicatum)

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Fast-growing underwater plant with long branched stems, feathery leaves, and small reddish flowers that stick up above the water. Grows in shallow and deep waters, tolerates intense heat and cold. Various theories about how it was introduced to the country — including that it came in ship ballast in the late 1800s or was used as packing material for worms sold to fishermen in Oklahoma.

Fanwort

(Cabomba caroliniana)

Underwater plant with long, hairy, branching stems and fan-shaped leaves; occasional floating leaves at the water’s surface are diamond-shaped. Usually grows in less than 10 feet of water, but can grow at depths of up to 30 feet. Reproduces mainly through “fragmentation” — bits of the plant taking root. The fragments can be transported long distances on boats, boat trailers, birds, or flowing water.

Hydrilla

(Hydrilla verticillata)

Fast-growing underwater plant with long, slender stems that branch out when they reach the water’s surface and whitish roots with potato-like tubers at the tips. Female flowers are white with six petals and float on the surface. Male flowers are greenish. Leaves — arranged in whorls of four to eight — are inch long with pointed tips and saw-toothed edges. Can grow an inch a day in deep or shallow water. Believed to have entered the country in Florida as an aquarium plant in the 1950s.

Water Chestnut

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(Trapa natans)

Water chestnut.

Department of conservation and recreation

Water chestnut.

Rooted, floating plants that form dense mats on the water’s surface. Triangular leaves form rosettes with shiny upper sides and hairy under sides. An air bladder is located at the base of the floating leaves. Small white flowers develop from July until the first frost, and small nuts are armed with four very sharp barbs. In a single season, an acre of water chestnut can produce enough seeds to cover 100 acres of water the following year.

Phragmites

(Phragmites australis)

Tall grass that forms dense barriers above ground and dense mats of roots underground. Can reach up to 16 feet high with silky flower plumes that start out purple and turn white and fluffy, often drooping to one side. Name comes from the Greek word phragma, which means fence.

SOURCE: Massachusetts Department of Conservation and Recreation’s Lakes and Ponds Program   Illustrations from Department of Conservation and Recreation, USDA-NRCS PLANTS Database

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