by Lynden Gerdes, MBS Botanist/Ecologist
Canadian rice-grass (Piptatherum canadense) (Poiret) Torrey - First vouchered from Minnesota in 2003. Several locations of plants were documented from the Laurentian Uplands subsection in Lake County. Barkworth is a synonym for this species.
This distinctive grass occurs primarily in boreal eastern North America, distributed from Newfoundland to Alberta and reaching the southern edge of its range in the central Rocky Mountains, the northern Great Lake States of Minnesota, Wisconsin and Michigan, and the mountains of New York and New England. Several disjunct populations also occur in West Virginia and South Carolina. See Nature Serve and Robert Freckman Herbarium.
Canadian rice-grass is known to occur in a variety of habitat conditions including: dry, sandy or rocky woods and hillsides; sandy open ground with jack pine and white spruce; barrens; thin woods and mountain-slopes (Voss 1972, Gleason and Cronquist 1991, Scoggan 1978). In Michigan, disturbance sites, such as logged areas and road margins, resulting in the exposure of sandy, moist ground, are not uncommon habitats for this species. Select disturbance habitats may provide refugia for this species by imitating natural disturbance events such as fire, windthrow, and erosion. Wetland ecotones that remain open from fluctuating water levels may also provide favorable conditions for this species (Penskar 1993).
The Minnesota populations primarily occur on sandy and sandy-gravel soils. Habitat conditions are variable and range from scattered patches of rice-grass occurring at top of a narrow, steep, esker of red pine (Pinus resinosa), paper birch (Betula papyrifera) and trembling aspen (Populus tremuloides); borders and center of brushy, abandoned logging trails; younger pine plantations; thinned mixed forest of white pine (Pinus strobus), red pine, white spruce (Picea glauca), trembling aspen and paper birch; and dozens to hundreds of clumps of rice-grass were observed in openings and clearings of various sizes (< 1 to 9 acres). The six or so populations of Canadian rice-grass currently known to occur in Minnesota are located within a 1 x 3 square mile area.
Recommendations for additional searches and survey in northern Minnesota should include upland sites having an open to scattered canopy and dry to moist soils of sand, gravel or rock. Associated species may include: red pine, jack pine (Pinus banksiana), white pine, white spruce, black spruce (Picea mariana), trembling aspen, paper birch, dwarf bilberry (Vaccinium cespitosum), mountain rice-grass (Oryzopsis asperifolia), sharp pointed rice-grass (Oryzopsis pungens), poverty grass (Danthonia spicata), and grapeferns (Botrychium spp.). Peak search time in northeastern Minnesota is likely from early to mid July, and potentially extending into early August.
Status in Minnesota
This concentration of 6 or so populations of plants are currently the only known locations for this species in the State. This new addition to our State flora is currently undergoing review for potential listing as Minnesota Endangered, Threatened, or Special Concern.
If you are so fortunate to encounter this species during one of your botanical treks, please record its location and contact the Natural Heritage Program for additional information.
Fernald, M. L. 1950. Gray's Manual of Botany. 8th edition. American Book Company. New York. 1632 pp.
Gleason, H.A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Canada. 2nd ed. The New York Botanical Garden. Bronx, NY. 910 pp.
Penskar, M. 1993. Element Stewardship Abstract for (Oryzopsis canadensis) Canada mountain rice-grass. The Nature Conservancy. Arlington, Virginia. 11pp.
Scoggan, H. J. 1978. The Flora of Canada. Nat. Mus. Nat. Sci. Publ. Botany. 4 vol., 1711 pp.
Voss, E. G. 1972. Michigan Flora. Part I. Gymnosperms and Monocots. Bull. Cranbrook Insti. Sci. 55 and Univ. of Michigan Herbarium. 488 pp.