Scutellaria ovata var. versicolor (Nutt.) Fern.
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Scutellaria ovata ssp. ovata
Basis for Listing
Scutellaria ovata var. versicolor is a rare species of hardwood forests in southeastern Minnesota. It reaches the state at the northern terminus of its range and is apparently limited to habitats in the Mississippi River valley and a few major tributaries. When it was listed as a special concern species in Minnesota in 1984, there were so few recent records it was thought that a serious population decline had occurred. However, a thorough survey of its habitat had not been completed. Since that time, a biological survey of the southeast has been completed and only 7 populations were found. None of the sites recorded in the 1880s and 1890s have been relocated. The apparent decline is probably associated with the destruction of this species' fragile woodland habitat. Scutellaria ovata var. versicolor was subsequently reclassified as a threatened species in 1996.
This tall, woodland perennial has stout, erect stems up to 7 dm (27.5 in.) tall, with spreading glandular hairs. The thin, long-petioled leaves are cordate at the base and usually have 12 or more teeth on each side. The bracteate leaves are regularly shorter than the calyx, almost always sessile and entire, and easily distinguished from the adjacent foliage leaves. Blue to purple flowers are in terminal racemes or racemes that arise from the axils of upper leaves. (Gleason 1963; Gleason and Cronquist 1991).
In Minnesota, S. ovata var. versicolor seems to prefer mixed hardwood forests, bottomland and floodplain forests, oak woodland, and the transition zone between floodplain and oak woodland. It is often associated with Acer saccharinum (silver maple), Tilia americana (basswood), Ulmus americana (American elm), Quercus rubra (red oak), or Quercus macrocarpa (bur oak). Scutellaria ovata var. versicolor seems to occur in small patches of up to 50 plants.
Biology / Life History
Scutellaria ovata var. versicolor is actually a species complex with many published subspecies or varieties. All are limited to the central and eastern states, but only variety versicolor (Nutt.) Fern. occurs in Minnesota (Gleason and Cronquist 1991). Plants emerge in late spring and flower from late June through July. Fruits develop in July and August.
Conservation / Management
Any management activities that occur in the vicinity of known S. ovata var. versicolor populations should be planned with extreme caution to avoid direct or indirect habitat alterations. Its woodland habitats may be impacted by certain agricultural practices, animal grazing, certain logging practices, road building, and river control structures. In addition to the potential for direct damage to plants and to the soil from heavy equipment, large canopy openings can increase the amount of solar energy reaching the forest floor. The subsequent drying and warming of the soil can alter the habitat enough to shift the competitive balance among plant species within the forest community. Such habitat changes could be very detrimental to the future of this rare species. Invasion by the non-native Phalaris arundinacea (reed canary grass) can also lead to the decline of all understory plants including S. ovata var. versicolor.
Conservation Efforts in Minnesota
The Minnesota DNR Biological Survey has been completed in the range of this species in the state. Some populations occur in State Parks where they are protected from most threats. Other populations are on State Forest lands and National Wildlife Refuges, where resource management plans should incorporate habitat protection needs for this rare species.
Gleason, H. A. 1963. The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. Three volumes. Third printing, slightly revised. Hafner Publishing Company, Inc., New York.
Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.
Minnesota County Biological Survey. 1994. Natural communities and rare species of Houston County. Biological Report No. 50. Minnesota Department of Natural Resources, St. Paul, Minnesota.
Minnesota County Biological Survey. 1994. Natural communities and rare species of Winona County. Biological Report No. 49. Minnesota Department of Natural Resources, St. Paul, Minnesota.
Minnesota County Biological Survey. 1995. Natural communities and rare species of Goodhue County. Biological Report No. 44. Minnesota Department of Natural Resources, St. Paul, Minnesota.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis, Minnesota. 320 pp.