Heteranthera dubia (Jacq.) MacM.
Habitat: Damp sands, often submerged in quiet waters. [Open water (non-forested, wetland)]
Range: Southern Quebec to North Dakota and Washington, south to Cuba and South America.
Aids to Identification: This perennial aquatic plant usually grows in shallow water with its stem submersed. The leaves are grass-like and up to 15 cm long. The flowers are pale yellow, and the fruits are black. It can be recognized vegetatively by its alternate, narrow, parallel-sided leaves with many fine veins. The leaves lack a more prominent central vein.
Ecological characteristics: In Maine, this species may occur along shallow shorelines or in open water.
Phenology: Flowers June - September.
Synonyms: Commelina dubia Jacq.; Heteranthera graminea (Michx.) Vahl; Zosterella dubia (Jacq.) Small.
Known Distribution in Maine: This rare plant has been documented from a total of 15 town(s) in the following county(ies): Aroostook, Hancock, Kennebec, Penobscot, Somerset, Waldo.
Reason(s) for rarity: At northern limit of range.
Conservation considerations: Maintain water quality in the lakes and ponds in which it occurs.