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Hippuris vulgaris


Mare's tail colony
mare's tail in-situ

Habitat: Mares tail grows in the emergent to submersed plant community, generally in muddy substrates, along damp shores and in shallow, quiet waters of ponds and streams. This plant may occur in fresh or brackish water, and prefers non-acidic conditions.

Description:The simple, unbranched stems of mares tail emerge along stout, spongy, creeping rhizomes. Ribbon-like leaves (length 1 to 10 cm) are entire, and attached at the base with no leaf stem (petiole). The leaves occur in whorls of 6 to 12 leaves, with whorls more closely spaced toward the growing tip. The top part of the stem often emerges from the water. The emergent leaves are linear, with blunt, hard tips. The submersed leaves are generally more elongate, more flaccid and sometimes paler than the emergent leaves. Tiny inconspicuous flowers occur in the axils of the middle and upper leaves.

This is the only aquatic plant native to Maine with blade-shaped leaves occurring in whorls of more than three leaves. This feature may cause this plant to be confused with two of the invasive plants on Maines invasive aquatic plant list: hydrilla and Brazilian waterweed. Unlike both hydrilla (with its finely but conspicuously serrated leaves) and Brazilian elodea (with its minutely serrated leaves), the leaves of mares tail are strictly entire (smooth edged). Also, both hydrilla and Brazilian elodea branch freely as they grow. Mares tail may branch at the base where it emerges from the rhizome, but otherwise grows throughout the season on simple, unbranched stems.

Mare's tail Range Map
U.S. range map of mare's tail

U.S. Range: Mares tail is native to Maine, New England and much of the United States. Mares tail is considered rare in Maine.

Mare's tail stem
Two stems showing unbranching habit;
lower (submersed) leaves are flaccid;
upper (emergent) leaves are stiff.

Annual Cycle: Mares tail is a perennial, with stems emerging anew from stout rhizomes each spring. Flowers occur from June through September, however sexual reproduction (propagation by seed) is considered to be rare. The primary means of reproduction is asexual, through rhizome division and spread.

Value to the Aquatic Community: Mares tail offers habitat and food to various species of fish and invertebrates.

Look Alikes: May be confused with hydrilla, Brazilian waterweed, commmon waterweed, and slender waterweed. The emergent tips of mare's tail may be confused with the flowering emergent spikes of some water-milfoils.

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Mare's tail specimen Mare's tail in-situ Mare's tail whorl Mare's tail range map Mare's tail stem Mare's tail habit

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