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Yellow iris might be mistaken for simply a yellow variant of blue flag iris, but the two species are distinct. Yellow iris has basal leaves longer (3-4') than the flower stalk; both prefer wetlands and shallow water. The leaf venation is parallel, typical for a monocot. As you would expect, the flowers are yellow with golden patches. Each flower stalk bears branches that terminate in clusters of 2-3 flowers. Each flower is 3-4" across and consists of: (1) three yellow sepals (the "falls") drooping towards their ends with a conspicuous golden spot (the "signal") whose edge is outlined by a series of brown to maroon spots or lines; (2) directly above the sepals are three yellow petal-like style branches (the "style arms") with upturned tips (the "style crests") (the stigma, where pollen is captured, is located at the fold between the style arms and crests); and, (3) between the sepals are three very short yellow petals (the "standards") that barely rise up above the plane of the sepals and style branches. The stamens are located under the style arms. The seed capsules are three-lobed, elongate (3") ovals that contain seeds that float on the water when released. Yellow iris is an introduced plant from Europe, now naturalized.

Iris

Iris pseudacorus

yellow iris [Blooms: May-Jun]

Iris virginica is the typical "blue flag" iris; it is an impressive plant 2-3' tall that prefers wetlands and shallow water. Each flower is 3-4" across consisting of: (1) three sepals (the "falls") that whose ends droop, each with a conspicuous bright-yellow spot (the "signal") and blue lines lead from the edges of the sepal into the signal; (2) directly above the sepals are three blue-violet petal-like style branches (the "style arms") with upturned tips (the "style crests") (the stigma, where pollen is captured, is located at the fold between the style arms and crests); and, (3) between the sepals are three petals with dark purple veins (the "standards") that rise up above the plane of the sepals and style branches. A green, ovoid ovary occurs at the base of the sepals and petals. The stamens are located under the style arms. The seed capsules are three-lobed, elongate ovals 2-3" long that contain seeds that float on the water when released. Blue flag iris (Iris virginica) is native to Illinois and Missouri, but it is sometimes confused with the very similar Iris versicolor; however, the Illinois Department of Natural History does not recognize Iris versicolor as occurring in Illinois. (It is present in Wisconsin and Minnesota.)

Iris

Iris virginica

blue flag iris [Blooms: May-Jun]