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Proserpinaca palustris and Proserpinaca pectinata


Common mermaid weed colony
Common mermaid weed in-situ

Habitat: Mermaid weed grows in the submersed and emergent plant communities. It may be found in the shallow waters of bogs, marshes, swamps, and along the muddy shores and banks of ponds and streams. The plants are well adapted to life at the water's edge and may morph to a terrestrial form when water levels drop.

Description: Maine is home to two mermaid weed species: common mermaid weed (Proserpinaca palustris) and comb-leaf mermaid weed (Proserpinaca pectinata). The green- to reddishbrown stems of both species emerge from long trailing rhizomes. Stems may lie prone along the bottom for some distance, then curve upward toward the water surface. Mermaid weeds have two distinct leaf types: submersed and emergent. The submersed leaves of both species are similar, 5 to 10 cm long, and finely feather-divided. Some of the hairlike leaflets may be forked or appear barbed. The leaves are arranged in a radiating alternate pattern (not whorled). The primary distinction between the two mermaid weed species is found in the emergent leaves (the leaves associated with flowering and fruiting). The emergent leaves of P. palustris are blade-shaped and conspicuously serrated. The emergent leaves of P. pectinata are feather-divided to pinnately lobed. Changing water levels may produce alternating sets of the two leaf types. The reddish-purple flowers (2 cm wide) occur in the leaf axils of the emergent leaves, followed by three-sided fruits, or nutlets.

Common mermaid weed Range Map
U.S. range map of common mermaid weed

Comb-leaf mermaid weed Range Map
U.S. range map of comb-leaf mermaid weed

U.S. Range: Both mermaid weed species are native to Maine and New England, much of the Eastern United States and the gulf coast states. Proserpinaca pectinata is listed as rare in Maine.

Annual Cycle: Mermaid weed is an aquatic perennial that propagates from seed, and by spreading roots and rhizomes. Plants die back to the roots and rhizomes as winter sets in. New growth emerges from the seeds and rhizomes in the spring. Flowers occur by mid-summer.

Mermaid weed leaf
Submersed leaves are feather-divided;
leaflets may be forked

Value to the Aquatic Community: Shorebirds and waterfowl feed upon the seeds of mermaid weed, and aquatic invertebrates and fish use the trailing leaves and stems for food and shelter.

Look Alikes: The submersed leaves of mermaid weed may be confused with leafy water-milfoils. Mermaid weed's alternate leaf arrangement and forked leaflets help to distinguish it from the milfoils.

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Mermaid weed leaf common mermaid weed in-situ Comb-leaf mermaid weed range map Common mermaid weed range map Common mermaid weed illustration Comb-leaf mermaid weed illustration

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