Eleocharis engelmannii Steud.
Habitat: Wet sand, peat, or mud [non-forested, wetland].
Range: Maine south to Georgia and Louisiana, west to California, north to Alberta and Ontario.
Aids to Identification: Spikerushes are recognized by their inconspicuous basal leaves and a single spike inflorescence terminating a leafless stem. Identification primarily relies on the microscopic characteristics of the tubercle (a small appendage at the summit of the achene). Mature fruit is critical for proper identification. Engelmann’s spikerush can be distinguished from other Maine spikerushes based on the following features: an articulated tubercle that is not constricted at the base, fibrous roots (annual), a narrow-cylindric spike, and very short perianth bristles.
Ecological characteristics: Historic locations of this plant in Maine include shores of ponds and streams.
Phenology: Fruiting in Maine in summer into fall.
Synonyms: Tracked in Maine at the species level, though two varieties are present.
- Eleocharis engelmannii Steud. var. detonsa Gray in H. Patters, with synonyms Eleocharis monticola Fern. var. leviseta Fern. and Eleocharis obtusa (Willd.) J.A. Schultes var. detonsa (Gray) Drapalick & Mohlenbrock.
- Eleocharis engelmannii Steud. var. engelmannii with synonyms Eleocharis monticola Fern. and Eleocharis obtusa (Willd.) J.A. Schultes var. engelmannii (Steud.) Britt.
Known Distribution in Maine: This rare plant has been documented from a total of 2 towns in the following counties: Cumberland, Oxford
Reason(s) for rarity: At northern limit of range.
Conservation considerations: Unknown, has not been seen in Maine in several years.