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Stuckenia filiformis (Pers.) Boerner ssp. occidentalis (Robbins) Haynes, D.H. Les & M. Kral

Slender Pondweed

Habitat: Alkaline ponds and streams. [Open water (non-forested, wetland)]

Range: Nova Scotia and southern Canada, south to Maine, Michigan, Texas, Colorado and New Mexico (ssp. occidentalis).

Aids to Identification: Stuckenia filiformis ssp. occidentalis is a pondweed with floating leaves absent and submersed leaves linear. Stipules connate to leaf sheaths for at least 1 cm. Leaves are 0.5-2 mm wide, not lobed at base, tips blunt, obtuse, or notched (rarely apiculate). S. filiformis ssp. occidentalis is large, 30-100 cm long; stipules on lower stem are loose and soon disintegrating.

Ecological characteristics: In Maine, this species is mostly restricted to a few marl ponds of Aroostook county. Marl ponds are themselves rare in Maine. Sites where these plants have been found range in pH from 7.3 to 9.1. The variety occidentalis is far rarer than the variety alpinus.

Phenology: A perennial; fruits (often helpful for identification) ripen in August - September.

Family: Potamogetonaceae

Synonyms: Formerly known as Potamogeton filiformis Pers. var. occidentalis (J.W. Robbins) Morong; Coleogeton filiformis (pers.) D.H Les & R. Haynes ssp. occidentalis (J.W. Robbins) D.H. Les & R. Haynes

Known Distribution in Maine: This rare plant has been documented from a total of 3 town(s) in the following county(ies): Aroostook.

Dates of documented observations are: 1979, 1992, 1994, 1998

Reason(s) for rarity: Habitat naturally scarce in Maine.

Conservation considerations: Maintain hydrologic integrity of its alkaline water habitat.

For more information, see the New England Wild Flower Society's Conservation Plan for Stuckenia filiformis ssp. occidentalis-pdf link-417 KB.