- Scientific name: Sisyrinchium mucronatum Michx.
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Endangered (MA Endangered Species Act)
Description
Slender blue-eyed grass, a member of the iris family (Iridaceae), is a low, dark green, grass-like perennial. Its unbranched scape (naked flowering stem) is thin, wiry, narrowly winged, and 1.5-4.5 dm (0.6-1.5 ft) high. The very narrow, 1-2 mm (0.1 in) broad leaves are much shorter than the scape. Blue to violet flowers, each with a yellow to greenish-yellow "eye," occur in a cluster at the scape's terminus. A red-purple—or, rarely, green—spathe (modified leaf sheathing an inflorescence) extends beyond the cluster of flowers. The plant's capsules (dry fruits derived from a compound pistil which contain many seeds) are globose in shape and 2-4 mm (0.1-0.2 in) long. Slender blue-eyed grass flowers from mid-May to June.
Meadow blue-eyed grass (Sisyrinchium montanum) is the only other blue-eyed grass in Massachusetts that normally has an unbranched scape. However, its leaves are much wider, 3-4 mm (0.2 in) wide, and are a light shade of green, and its capsules are larger. Finally, the red-purple spathe of slender blue-eyed grass is seldom seen in other Sisyrinchium species. Although not a large genus, it is very conservative in its features, and it takes practice to separate and identify the species. It is recommended that one use a technical manual to identify the plants to species.
Life cycle and behavior
This is a perennial species.
Population status
Slender blue-eyed grass is listed under the Massachusetts Endangered Species Act as endangered. All listed species are protected from killing, collecting, possessing, or sale and from activities that would destroy habitat and thus directly or indirectly cause mortality or disrupt critical behaviors. MassWildlife’s Natural Heritage & Endangered Species Program database has 6 records from 1 county (Berkshire). Five of those records have been confirmed since 1999.
Photo credit: Bruce Sorrie
Distribution and abundance
Slender blue-eyed grass has a spotty distribution. It is known from New Brunswick across southern Canada to Saskatchewan, south along the Atlantic coastline to Georgia and Louisiana. Although not a coastal species, it is not known in many of the mid-western states, and has not been evaluated in most states where it does occur. In New England, it is potentially extirpated in New Hampshire and Vermont, critically imperiled in Massachusetts, and not known in Rhode Island. There is no ranking for the species in either Connecticut or Maine (NatureServe 2025).
Habitat
Preferred habitats are sunny, calcium-rich wetlands. These include fields, meadows, borders of calcareous fens (wet, generally open areas where cold, calcium-rich water seeps to the surface) and occasionally moist roadsides with limey soils. Current sites in Massachusetts include a wet meadow, an open, alkaline seepage fen (an unforested, peat-forming habitat where very cold, nutrient-poor water seeps through limey gravel to the surface), and a shallow roadside ditch. Associated species in the graminoid ground cover include various sedges, among them yellow sedge (Carex flava), Bush's sedge (Carex bushii, endangered), small yellow sedge (C. cryptolepis), fen cotton-grass (Eriophorum viridicarinatum) and old-field species such as timothy (Phleum pratense) and goldenrods (Solidago spp.).
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Threats to the species include general reforestation, loss of meadow habitats, and spread of invasive species.
Conservation
Several of the sites are mowed on a regular basis to keep them open and to keep invasive shrubby plants under control. The timing and frequency of the mowing should be reviewed for effects on the rare species and the habitats. Invasive non-native species occur at all the sites. Sites should be monitored for invasions of exotic plants; if exotic plants are crowding and outcompeting this species, a plan should be developed in consultation with MassWildlife’s Natural Heritage & Endangered Species Program, to remove the invaders. All active management of rare plant populations (including invasive species removal) is subject to review under the Massachusetts Endangered Species Act and should be planned in close consultation with the Natural Heritage & Endangered Species Program.
References
Gleason, Henry A., and Arthur Cronquist. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition. Bronx, NY: The New York Botanical Garden, 1991.
Haines, A. 2011. Flora Novae Angliae – a Manual for the Identification of Native and Naturalized Higher Vascular Plants of New England. New England Wildflower Society, Yale Univ. Press, New Haven, CT.
NatureServe. 2025. NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. Accessed: 6/9/2025.
POWO (2025). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; https://powo.science.kew.org/ Accessed: 6/9/2025.
Contact
| Date published: | May 7, 2025 |
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