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Iris prismatica (Slender blue iris)
Cressler, Alan

Iris prismatica

Iris prismatica Pursh ex Ker Gawl.

Slender Blue Iris, Slender Blue Flag, Coastal Iris

Iridaceae (Iris Family)

Synonym(s): Iris carolina, Iris prismatica var. austrina

USDA Symbol: irpr

USDA Native Status: L48 (N), CAN (I)

Thin, grass-like leaves rise from a basal cluster to 1-2 ft. The typically iris-like blossom, occurring on a branched stem, is pale blue to violet.

A member of the iris family (family Iridaceae) which consists of herbs growing from rhizomes, bulbs, or corms, with narrow basal leaves and showy clusters at the tips of long stalks. There are about 60 genera and 1,500 species, distributed in temperate and tropical regions. Among them, Iris, Freesia, Gladiolus, Bugle Lily, and Montbretia are popular ornamentals. Saffron dye is obtained from Crocus, and "essence of violets," used in perfumes, is extracted from the rhizomes of Iris.


From the Image Gallery

7 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Herb
Fruit Type: Capsule
Size Notes: Flower stems up to about 32 inches tall.
Fruit: Green, Brown

Bloom Information

Bloom Color: White , Blue , Violet
Bloom Time: Apr , May , Jun , Jul


USA: CT , DE , GA , MA , MD , ME , NC , NH , NJ , NY , PA , RI , SC , TN , VA , VT
Canada: NS
Native Distribution: Coastal areas from N.S. to GA; also s. Appalacians
Native Habitat: Brackish to fresh swamps & meadows near the coast

Growing Conditions

Light Requirement: Part Shade
Soil Moisture: Moist
Soil Description: Moist, acid soil.
Conditions Comments: Will tolerate high pH soils.


Warning: POISONOUS PARTS: Rhizomes (thickened roots) and rootstocks, fresh or dry. Minor skin irritation when touched, low toxicity if ingested. Symptoms include nausea, vomiting, abdominal pain, diarrhea, elevated temperature following ingestion; skin irritation upon contact with seeds, rootstock, or cell sap. Toxic Principle: Irisin, iridin, or irisine. (Poisonous Plants of N.C.)

Attracts: Birds


Description: Sow seeds outside as soon as they are ripe. Seedlings will germinate in one year and flower in two. Propagation is also accomplished by division.
Commercially Avail: yes

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Mt. Cuba Center - Hockessin, DE

Web Reference

Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Iris prismatica in USDA Plants
FNA: Find Iris prismatica in the Flora of North America (if available)
Google: Search Google for Iris prismatica


Record Modified: 2023-02-14
Research By: TWC Staff

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