Stuckenia filiformis (Pers.) Boerner ssp. alpinus (Blytt) Hayer, Les & Kral
Northern Slender Pondweed
Habitat: Alkaline ponds and stream. [Open water (non-forested, wetland)]
Range: Greenland to Alaska, south to northern New England, New York, and west to Utah (ssp. alpinus).
Aids to Identification: Stuckenia filiformis ssp. alpinus is a pondweed with floating leaves absent and submersed leaves linear. Stipules are fused to leaf sheaths for at least 1 cm. Leaves are 0.2-0.8 mm wide, not lobed at base, tips blunt, obtuse, or notched (rarely apiculate). S. filiformis spp. alpinus is 10-30 cm long, with tightly clasping, persistent leaf sheaths.
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.
Synonyms: Formerly known as Potamogeton filiformis Pers. var. alpinus (Blytt) Aschers. & Graebn.; Coleogeton filiformis (Pers.) D. Les & R. Haynes ssp. alpinus (Blytt) D. Les & R. Haynes
Known Distribution in Maine: This rare plant has been documented from a total of 12 town(s) in the following county(ies): Aroostook.
Dates of documented observations are: 1940 (2), 1972 (2), 1973 (2), 1979 (4), 1998, 1999 (2), 2002
Reason(s) for rarity: Southern limit of range; suitable habitat naturally scarce.
Conservation considerations: Maintain hydrologic integrity of its alkaline water habitat.