Sisyrinchium montanum
A clump-forming, grass-like perennial in the iris family, producing violet-blue star-shaped flowers with yellow centres from late spring through mid-summer. Native to moist sandy meadows and open woods across Canada and the northern United States.
Bloom & Fruit
Six-tepaled, violet-blue, star-like flowers approximately 2 cm across. Each flower has a yellowish base and prominent yellow stamens. Flowers are borne in small cymes of 2-5, emerging from a papery spathe at the tip of long, winged flowering stalks.
Growing Conditions
Garden Uses
- Pollinator HostAttracts bees, butterflies, and beneficial insects. Plant near vegetable gardens to boost pollination.
Where to Buy
Ecology
Native Habitats
Propagation
- Seed (direct sow, no pre-treatment)
Details
Description
Sisyrinchium montanum is a clump-forming, grass-like perennial that belongs to the iris family (Iridaceae) rather than the grasses, despite its common name. It grows 10-50 cm tall from a short rhizome, with slender, bright green basal leaves only about 3 mm wide. The stems and leaves are flattened and winged, with finely toothed margins, resembling those of a small rush or sedge.
The flowers are the plant's most distinctive feature: six violet-blue to purple tepals form a flat, star-shaped bloom roughly 2 cm across, with a yellowish centre and prominent yellow stamens. Flowers open singly or in small clusters of two to five at the tip of each flowering stalk, emerging from a papery, iris-like spathe. Each bloom lasts only a day, but plants produce flowers in succession over several weeks.
Two varieties are recognized: the widespread var. montanum and the less common var. crebrum. The species closely resembles Sisyrinchium angustifolium (Narrow-leaved Blue-eyed Grass) and the two are sometimes confused or combined in treatments.
Growing Conditions
Prefers full sun and moist to mesic, sandy soils. Naturally found in moist sandy meadows, open woods, prairie edges, and along stream banks. Tolerates a range of conditions from dry to moist sites and from full sun to light shade, though flowering is most prolific in sun.
Widely adaptable across hardiness zones 3 through 8. Thrives in well-drained sandy or sandy-loam soils but tolerates periodic wetness (FACW to FAC wetland indicator status). An unusual member of the iris family in that it inhabits open grasslands rather than wetlands, though it appreciates consistent moisture during the growing season.
Phenology
Flowering extends from May through July, with peak bloom in June. Each individual flower opens for a single day, closing by afternoon, but the succession of buds on each cyme provides a display lasting several weeks. After pollination, small globular capsules develop, maturing from June through August. Capsules split open when ripe to release numerous small black seeds. Foliage remains green through summer and dies back in late fall. The plant overwinters as a dormant rhizome.
Ecology
The flowers attract a variety of small native bees, including species of Halictidae (sweat bees) and Andrenidae (mining bees), which serve as the primary pollinators. The open, radial flower form makes nectar and pollen accessible to short-tongued insects. Blue-eyed grass contributes to the pollinator diversity of prairie and savanna ground layers.
Seeds are dispersed by gravity and surface water flow. The plant reproduces both by seed and vegetatively through its short rhizomes, gradually expanding its clump over time. Foliage is occasionally browsed by deer and rabbits, though the plant is not a preferred forage species.
Propagation
Propagate easily from seed. Collect capsules as they begin to split in mid to late summer. Sow fresh seed directly on the soil surface in fall for natural cold stratification, or start indoors in late winter. Seeds require light for germination; do not cover deeply. Germination is typically reliable and does not require pre-treatment, though 30 days of cold-moist stratification may improve uniformity.
Clumps may be divided in early spring or fall every 3-4 years to maintain vigour. Divisions establish quickly in moist, well-drained soil. First-year plants may flower sparingly; full bloom is achieved by the second season.