southern blue flag

not listed

N5 - Secure

SNR - Unranked

not listed

OBL - Obligate wetland

OBL - Obligate wetland

OBL - Obligate wetland

Southern blue flag is a 20″ to 40″ tall, erect, perennial forb that rises on a single stem from a thick, creeping, freely-branching rhizome and fleshy roots. It often forms dense clumps.

The stems are erect to arching and usually have 2 or 3 branches. They seldom fall over after flowering. They are shorter than the leaves so that the leaves rise above the flowers.

Basal leaves are narrowly sword-shaped, green to grayish-green, 23½″ to 31½″ long, and 1″ to 13 ⁄16″ wide. They are erect and commonly arching near the top. There are 1 or 2 leaves on the stem subtending each branch. Stem leaves are similar to the basal leaves but shorter.

The inflorescence is 2 or 3 flowers at the end of the stem and 1 or 2 flowers at the end of the branch. The cluster emerges from an enveloping pair of large bracts (spathes).

The flowers are 3″ to 3½″ wide. There are 3 petals and 3 petal-like sepals, all of which are fused at the base into a ⅜″ to ¾″ long tube. Each sepal is egg-shaped to oval, widely spreading, arched, 1½″ to 2¾″ long, and ¾″ to 1½″ wide. It is abruptly or gradually narrowed toward the base (clawed) and broadly expanded toward the tip. It is pale blue to purple near the tip quickly fading to white with darker blue or purple veins toward the middle. There is a bright yellow patch near the throat. The claw is green in the center, surrounded by bright yellow, with purple veins. What appears to be an upper lip is actually a branch of the style. The highly modified style is enlarged and divided into 3 branches. Each petal-like style branch covers the lower portion of a one sepal, extending just beyond the narrowed claw and concealing the stamens. The style branch is 13 ⁄16″ to 1⅜″ long, distinctly ridged, and flared at the tip. It does not have ear-like lobes at the base. The 3 petals are smaller than the sepals. They are lance-shaped to spatula-shaped, erect, 1¼″ to 2¾″ long, and ⅜″ to 1¼″ wide. They are often notched at the tip. The flowers last 1 to 4 days and are somewhat fragrant. All white flowers are found, though rarely.

The fruit is a green, elliptical to egg-shaped, three-sided, 1¼″ to 2⅜″ long, ⅜″ to ¾″ in diameter capsule. It is rounded-triangular in cross section.

20″ to 40″

Lavender to violet

Wet. Meadows, swamps, marshes, and streambanks. In water less than 40″ deep. Full to partial sun.

May to July

Sources

2, 3, 4, 5, 7, 24, 28.

Native

Common

Southern blue flag iris, on the shore of Pickerel Lake

Found on the shore of Pickerel Lake

Plant

Inflorescence

Flower

Location: Mississippi National River and Recreation Area - Coldwater Spring

Location: Lilydale Regional Park

Southern blue flag iris, on the shore of Pickerel Lake

Location: Lilydale Regional Park

Found on the shore of Pickerel Lake