Iris virginica (Southern Blueflag)

Plant Info
Also known as: Virginia Iris
Family:Iridaceae (Iris)
Life cycle:perennial
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):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 3-petals

[photo of flower] 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: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of leaves] 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.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is an oblong, 3 angled capsule around 2 to 3 inches long and 1/3 to ½ as wide.


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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More photos

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.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Herb - George Crosby State Park
on: 2016-07-04 21:29:46

While hiking around Bensen Lake, I found the flower. This is on Northern Minnesota.

Posted by: K. Chayka
on: 2016-07-04 22:11:44

The Iris species in northeast MN is more likely northern blueflag, Iris versicolor

Posted by: Mary L - Rosemount
on: 2016-07-18 01:13:35

My yard. I started with 1 wild one and now have about 50.

Posted by: Gary - Grassy Point in Duluth
on: 2017-06-12 16:13:21

This species was planted as part of a "native wetland habitat restoration" along with several other species not native to the Northern Forest Bio-region.

Posted by: Bill - Arcola High Bridge
on: 2017-06-16 12:25:35

I saw a few this morning along the St. Croix River below the Arcola High Bridge.

Posted by: Aaron Pietsch - Fort Snelling SP
on: 2018-06-11 10:08:08

Lining the pond just north of Snelling Lake

Posted by: Ron Johannsen - Trenton Lake So. Mn.
on: 2020-06-04 19:08:53

Blue flag is blooming now along edge of marsh. So nice and showy.

Posted by: Jake Pearson - Big Lake
on: 2020-06-14 20:58:20

Map it, Blue Please...Sherburne County Two clusters 5 and 20

Posted by: K. Chayka
on: 2020-06-15 06:09:21

Jake, the county distribution maps are updated when populations are confirmed. The best way to do that is to submit a specimen to the Bell Herbarium, then it becomes part of the official record. You just need the landowner's permission to collect on their property.

Posted by: Renay Leone - Zimmerman, Sherburne County
on: 2023-06-14 16:59:40

It looks like we have both the north and south versions of the native iris here. I just saw patches of both (slightly different colors) along the edge of our tamarack bog today.

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