Iris virginica (Southern Blueflag)
|Also known as:||Virginia Iris|
|Habitat:||part shade, sun; open wetlands, lakeshores, wet ditches|
|Bloom season:||June - July|
|Plant height:||2 to 3 feet|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flowers are a typical iris shape, 3 to 4 inches across, blue to blue-violet, infrequently red-purple though often pale blue. The deeper colored edges of the 3 large, drooping petal-like sepals fade toward the base, with a bright spot of schoolbus yellow near the throat that is typically highly demarked from surrounding blue, and darker blue-purple veins radiating from it. The upper lip of the sepal is shorter and shaped like a shoehorn, curving up. Sepals are 1½ to 3¼ inches long and up to 1½ inches wide. The 3 petals are oblong to spatulate, 2/3 to nearly as long as the sepals, drooping to spreading or erect in the center. There are 1 to 3 flowers on a stalk.
Leaves and stems:
The sword-like leaves are mostly basal, about 1 inch wide and 1 to 3 feet long, erect or arching out from the base, sometimes purplish red at the base but more often brown. The few stem leaves often rise above the flowers. The flowering stems emerging from the base are smooth with a waxy surface (glaucous) and weak, often falling over in flowering. Stems are typically 1-branched.
Minnesota has two native irises appropriately named "northern" and "southern" Blueflag with their respective continental ranges overlapping in the southern half of the state. Iris virginica is the southern and predominant species from the Twin Cities all the way to the Texas coast. Iris versicolor similarily from the Twin Cities up into Canada. From our review of herbarium collections and field observations it would appear that Southern Blueflag is more common in the metro than reported, perhaps field identifications defaulting to Northern Blueflag. While very similar there are several distinguishing characteristics, though there is overlap so look at several before making a determination. Iris virginica is frequently lighter blue with less contrast between the darker colored sepals margins and throat, the veins less prominent with a sharply defined, school bus yellow spot in the throat. Iris versicolor is usually richly pigmented on the outer sepal margins, fading lighter towards the throat, the veins prominent but the throat a more poorly defined pale greenish yellow. Also I. virginica's center petals are 2/3 to nearly as long as the sepals, and the flower stalk weaker, often falling over while in flower. The petals on I versicolor are proportionately shorter, ½ to 2/3 the length of the sepals, the flower stalk firm and remaining upright at maturity. Stem leaves typically rise above the flowers on I. virginica and do not on I. versicolor. We would also note that many references (Gleason & Cronquist) note that the yellow spot on I. virginica is "hairy" while I. versicolor's is merely papillate (covered in minute, blunt hairs or protuberances). In our observations, both have very similar, dense, glassy papillate hairs that appear as a rough, solid surface, both to the naked eye and under a microscope. Neither species is what horticulturists would regard as hairy (i.e. a bearded iris).
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- sepal surface texture
Photos by K. Chayka taken at Sucker Lake, Ramsey County. Photos courtesy Peter M. Dziuk taken at Sucker Lake and at Blaine Preserve SNA, Anoka County.
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