: Blue lyme grass
: The species appears to be spreading following the lowering of Lake Michigan water levels; it invades beaches, dunes and other sites with sandy soils; stabilizes dunes, eliminating the shifting sands that are home to rare species such as Pitcher?s thistle (Cirsium pitcheri
: Perennial grass, stout, erect, growing from creeping rhizomes or in tufts, 0.5-1.5 m (1.5-5 ft) tall.
: Blue-glaucous, 6-15 mm wide, sheaths crowded at base, ligule barely 1 mm long.
: Blue-glaucous, hairless or nearly so at the summit.
: Arranged in a spike with 4-6 flowered spikelets usually paired at the nodes on spike.
Fruit and seeds
: Arranged in a spike, 15-25 mm thick.
: Native to Europe. It was introduced locally around the Great Lakes; thrives on calcium-rich sands; shade-intolerant; drought-tolerant; invasive on beaches and dunes.
: Primarily vegetative, spreading via its creeping rhizomes; may also reproduce by seed.
: Native thick-spike wheat grass (Agropyron dasystachyum
) is also blue-green but its spikes are only 5-10 mm thick; beach grass (Ammophila breviligulata
) is green rather than bluish; reed grass (Calamovilfa longifolia
) has a open panicle rather than a spike; American dunegrass (Leymus mollis
) is greener and finely hairy under the spike, while Lyme-grass is bluer and its stems are hairless almost to the top. A dichotomous key or consultation with an expert should be used to distinguish between these species as several are rare.
Monitoring and rapid response
: Monitor beaches and dunes adjacent to sites where this species has been used for landscaping. Lyme-grass can sprout from rhizomes and root fragments mechanical removal is not recommended; may be treated with herbicide in spring while native species are dormant; follow-up needed to ensure that all plants have been killed.
: The Michigan Natural Features Inventory
(MNFI) has partnered with MISIN to provide the information in this fact sheet. Species images and/or information were used with permission from "A Field Identification Guide to Invasive Plants in Michigan's Natural Communities
" and "A Field Guide to Invasive Plants of Aquatic and Wetland Habitats for Michigan