Carex oronensis

Common Names:
Orono sedge
Growth Habit:
CPC Number:
Profile Contributors:
Elizabeth J. Farnsworth
Fully Sponsored

Reference Links

ITIS - Tropicos - USDA Plants - Fish & WildLife

Participating Institutions

The following Participating Institutions are custodians for this species in the CPC National Collection:
New England Wild Flower Society

The conservation of Carex oronensis is fully sponsored.
Elizabeth J. Farnsworth contributed to this Plant Profile.


Carex oronensis is a sedge that grows in loose clumps up to a meter tall. It is endemic to a small area of Maine, and Maine's only known endemic plant species. Most of its 58 known populations contain few stems, with only a handful of populations encompassing more than fifty stems. Growing in fields, meadows, roadsides, and clearings, the plant is susceptible to disturbance and habitat conversion for development. It is regarded as imperiled in Maine because of its very limited distribution.

Research and Management Summary:
A handful of individuals and institutions have performed research on this species, and the New England Wild Flower Society is monitoring populations in Maine.

Plant Description:
This sedge is a member of the section Ovales in the Carex genus, and has the typically rounded inflorescences and winged perigynia (sacs enclosing the ovary) of that group. Three to four leaves, each 2-4 mm wide, occur on each fertile clump. Its sharply angled stems grow much taller than the leaves, which are narrow 3-5 mm wide). Well-developed scales are as long as the perigynia, which themselves are narrow and 2.9 to 4.3 mm long and 0.9 to 1.4 mm wide with straight styles and 2 red-brown stigmas (Fernald 1950, Gleason and Cronquist 1991, Haines and Vining 1998, Dibble and Campbell 2001). Mature perigynia are required to distinguish C. oronensis from C. scoparia var. tessellata or C. ovalis, but multivariate analyses of traits show that the species is clearly distinct (Dibble and Campbell 2001). A rust-colored blotch on the adaxial surface of the perigynium is a useful, unique field character. The roots and block and fibrous. The haploid chromosome number is n = 34 (Dibble and Campbell 2001) or n = 37 (Rothrock and Reznicek 1996).

Distribution & Occurrence


Conservation, Ecology & Research