Southern Blue Flag Iris

Iris virginica

Other common name(s):

Virginia Iris, Great Blue Flag

Family:

Iridaceae (Iris Family)

Plant Ecoregion Distribution Map

This map uses data from the US EPA. EPA  servers have been offline frequently so maps may not display. We are working on a solution.

Gulf Coast Prairies and Marshes, Western Gulf Coastal Plain
Bastrop Lost Pines, Floodplains and Low Terraces2, Northern Post Oak Savanna, Northern Prairie Outliers, San Antonio Prairie, Southern Post Oak Savanna
Northern Humid Gulf Coastal Prairies, Texas-Louisiana Coastal Marshes
Flatwoods, Floodplains and Low Terraces3, Pleistocene Fluvial Terraces, Red River Bottomlands, Southern Tertiary Uplands, Tertiary Uplands

Plant Characteristics

Growth Form

Wetland

Height

2
to
3
ft.

Spread

1
to
2
ft.

Leaf Retention

Deciduous

Lifespan

Perennial

Habitat and Care Requirements

Soil Type(s)

Rich, Moist

Light Requirement

Sun

Water Requirement

High

Native Habitat

Wetland or Riparian

Bloom and Attraction

Bloom Color

White, Yellow, Blue, Purple, Violet

Bloom Season

Spring, Summer

Seasonal Interest

Nectar, Pollen

Wildlife Benefit

Butterflies, Hummingbirds, Bees

Maintenance

Usually grows in large patches that expand outward from rhizomes. Will not bloom well if it has more shade than sun. It grows best in moist soils that are not too heavy but will tolerate some brief flooding early in the season and moderate dryness in late summer. Works well in rain gardens, edges of ponds, or lily pools. Native habitat: marshes, wet pinelands, swamps, wet meadows. WARNING: the roots and foliage are mildly toxic, so animals tend to not eat this plant. Propagation: seed, root division, clump division.

Comments

Blooms May-July. Grows from rhizomes, bulbs, or corms. Narrow basal leaves with stems that often lie on the ground after flowering. Three to four flowers are usually growing together. There is a yellow blotch on the lower sepal where it joins a small upper lip; a mark that helps to distinguish the flower from those of Iris versicolor, Northern Blue Flag Iris. The fruit is an oval capsule.
Material Treatment Method Collection References
Clump Division Divide in early fall when the leaves begin to turn yellow. Keep stringy roots attached to the rhizome sections. Transplant in the ground immediately. https://www.wildflower.org/plants/result.php?id_plant=IRVI
Seed No Treatment Sow in the ground immediately after collecting. Storage of iris seed greatly reduces viability. https://www.wildflower.org/plants/result.php?id_plant=IRVI

About the Region

Fall Symposium 2025 Logo - Teach for the Future

Salado, the location of our Fall 2025 Symposium, lies at the intersection of two ecoregions: the Edwards Plateau (Limestone Cut Plain) and Blackland Prairie (Northern Blackland Prairie).

The Edwards Plateau area is also called the Hill Country; however, this general term covers a much larger area extending farther north. Spring-fed creeks are found throughout the region; deep limestone canyons, rivers, and lakes (reservoirs) are common. Ashe juniper is perhaps the most common woody species found throughout the region. Additional woody species include various species of oak, with live oak (Quercus fusiformis) being the most common. Sycamores (Platanus occidentalis) and bald cypress (Taxodium distichum) border waterways. This area is well known for its spring wildflower displays, though they may be viewed in spring, late summer, and fall, as well. According to Texas Parks and Wildlife, average annual rainfall in the Edwards Plateau ranges from 15 to 34 inches.

The Blackland Prairie extends from the Red River south to San Antonio, bordered on the west by the Edwards Plateau and the Cross Timbers, and on the east by the Post Oak Savannah. Annual rainfall averages 30 to 40 inches, with higher averages to the east. This region is dominated by prairie species. The most common grass species include little bluestem (Schizachyrium scoparium) and Indian grass (Sorghastrum nutans) in the uplands and switchgrass (Panicum virgatum) in the riparian areas and drainages. Common herbaceous flowering plants include salvias, penstemons, and silphiums. This area has suffered greatly from overgrazing and agricultural use. Few intact areas remain, though many of the plants can be found along county roadsides throughout the region.

Our fall Symposium host chapter, the Tonkawa Chapter, includes both of these ecoregions.

Source: Wildflowers of Texas by Michael Eason