Isoetes prototypus D.M. Britt.

Prototype Quillwort

• State Rank: S1
• Global Rank: G2
• State Status: Threatened

Habitat: Shallow low nutrient ponds on sandy substrates. [Open water (non-forested, wetland)]

Range: New Brunswick, Nova Scotia, and Maine.

Aids to Identification: The various quillwort species can be difficult to identify because they are often distinguished by microscopic differences of the reproductive macro spores. The typical form of the quillworts is a dense rosette of narrow leaves with the spores located inside the widened leaf bases. I. prototypus has very straight, stiff, sharp-pointed, dark-green leaves that are mahogany-colored at the base. The megaspores are < 0.5 mm wide with a network of low, mound-like markings. This species is the only species in Maine in which the velum cover the entire sporangium.

Ecological characteristics: This quillwort is typically found growing alone or with very few other plant species, such as pipewort (Eriocaulon aquaticum). This habit may suggest that prototype quillwort is unable to tolerate competition from other plants or that its habitat requirements are quite restrictive.

Phenology: Perennial

Family: Isoetaceae

Synonyms: None Noted.

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

Reason(s) for rarity: Restricted range.

Conservation considerations: Maintain hydrologic integrity and water quality of pond habitat.