Description & Overview

Shreve’s Iris is a Wisconsin native perennial that in spring, forms clumps of green, sword-shaped foliage reaching three feet tall. By late spring to early summer, tall flower stalks emerge and open to a striking blue-violet fragrant flower. Deep purple veins and yellow splotches are found on most of the petals. After the flowers fade, inflated-looking seed pods appear, containing many brown seeds.

It is naturally found in wetlands and moist meadows in loamy soils. This variety looks similar to the species Iris virginica; however, var. shrevei prefers a more neutral soil, making it a better option for southeastern Wisconsin where our soil is more alkaline. Shreve’s Iris may also be known as Southern Blue Flag Iris.

Core Characteristics

Category: Perennial

Wisconsin Native: Yes

USDA Hardiness Zone: to zone 4

Mature Height: 1-3 feet

Mature Spread: 1-3 feet

Growth Rate: Moderate

Growth Form: Upright, colonizes, naturalizes

Light Requirements: Full Sun to Partial Shade

Site Requirements: Wet, well - drained, neutral soils

Flower: Fragrant, blue - purple, 6 - parted, 3" wide, yellow blotch, 3 petals, 3 sepals

Bloom Period: May – July

Foliage: Sword - like, erect, green to blue - green

Fall Color: None

Urban Approved: Yes

Fruit Notes: 3 - lobed capsule, 1 - 2" long, containing large brown seeds

Suggested Uses

Shreve’s Iris is excellent for wetland restoration projects. A wetland setting provides enough area for this species to naturalize while providing the consistent spring moisture level it needs. It can also be incorporated into stream banks, pond borders, ditches, or wet prairies where the soil remains wet at all times.

Ideal conditions for growing this plant may be difficult to obtain in a typical home landscape where the soil is drier; however, if there’s a pond, stream, or consistently moist rain garden on the property, it will grow easily. It is possible that Shreve’s Iris can go into dormancy early than expected if they are in a prolonged drought period. Supplemental water may be needed in such conditions.

With their height and unusual color, Shreve’s Iris make amazing cut flowers in mixed bouquets, or a grouping all on their own in a clear vase.

Shreve's Iris is a Wisconsin native perennial that in spring, forms clumps of green, sword-shaped foliage reaching three feet tall. By late spring to …
Shreve's Iris is a Wisconsin native perennial that in spring, forms clumps of green, sword-shaped foliage reaching three feet tall. By late spring to …

Wildlife Value

The flowers are pollinated by bumble bees (Bombus spp.) and long-horned bees (Synhalonia spp.).

The Iris Borer Moth (Macronoctua onusta) feeds exclusively on the corms of Irises. Weevils (Mononychus vulpeculus) feed on the seeds.

Shreven’s Iris is a host plant for the Virginia Ctenucha moth (Ctenucha virginica) and Agreeable Tiger moth (Spilosoma congrua).

Other visitors include Two-spotted Skippers (Euphyes bimacula), Artic Skippers (Carterocephalus palaemon), Dion Skippers (Euphyes dion), thrips, mealybugs, Syrphid flies, Agromyzid flies, and aphids.

Maintenance Tips

Divide clumps every couple of years in the early fall when the leaves begin to yellow. Be sure to wear gloves as some people have a sensitivity to the plant’s juices, causing blisters on the skin.

Shreve's Iris is a Wisconsin native perennial that in spring, forms clumps of green, sword-shaped foliage reaching three feet tall. By late spring to …

Pests/Problems

Black Walnut Tolerant: Yes
Deer Resistant: Yes
Rabbit Resistant: Yes

Shreve’s Iris is toxic to dogs, cats, and horses.

It is rarely bothered by pests or diseases, making it a low-maintenance choice.

The rhizomes may be eaten by muskrats.

Leaf Lore

The genus Iris was named by the Greeks for the goddess of the rainbow. Iris had the duty of leading the souls of women to the Elysian fields after they died by means of a rainbow bridge. Greeks placed iris blooms on women’s graves. The specific epithet virginica means “of Virginia.”

Similar to Harlequin Blue Flag Iris (Iris versicolor), there is a lot of variation in flower color for this plant. Colors range from light blue to deep violet, but rarely white. In all cases, the color is beautiful!

After the seed pod opens, they float on water and are carried to new locations, aiding in its dispersal.
They can grow in water up to a foot deep!

The Cherokee people made an infusion of the plant to ease liver ailments. Roots were pulverized and used as a salve to treat ulcers.

Some plants can absorb toxic substances such as herbicides, pollutants, and pesticides from the air, water, and soil. The Iris family (Iris spp.) is known to degrade herbicides, specifically Atrazine, and has been used as a hydraulic control slowing the movement of contaminated groundwater.

Roots were commonly used as a cathartic by Native Americans.

Companion Plants

Plant Shreve’s Iris with those that enjoy similar moist to wet site conditions. A few options include Palm Sedge (Carex muskingumensis), Harlequin Blue Flag Iris (Iris versicolor), Black Willow (Salix nigra), Great Blue Lobelia (Lobelia siphilitica), Cardinal Flower (Lobelia cardinalis), Buttonbush (Cephalanthus occidentalis), White Turtlehead (Chelone glabra), Spotted Joe-Pye Weed (Eutrochium maculatum), Swamp Milkweed (Asclepias incarnata), Tamarack (Larix laricina), Bog Birch (Betula pumila), Riddell’s Goldenrod (Solidago riddellii), Speckled Alder (Alnus incana var. rugosa), Steeplebush (Spiraea tomentosa), and Sweetgale (Myrica gale).

Shreve's Iris is a Wisconsin native perennial that in spring, forms clumps of green, sword-shaped foliage reaching three feet tall. By late spring to …
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Written by Beth DeLain