aLTERNATIVE

Dangers Of and Alternatives to the Dutch Iris

Invasive plant

IRIS PSEUDACORUS FLOWER, DUTCH IRIS

• This invasive species, native to Europe and west Asia, has been planted as an ornamnetal due to its showy yellow blooms and dense green stands in the summer.

• It is easily identified by its large yellow flowers and prominent raised midrib on the leaf.

• This iris grows quickly to form dense, monotypic stands that reduce diversity and can alter waterways.

• The roots and leaves are poisonous, both to wildlife and livestock. It is a Tier 1 invasive species in Louisiana deemed as “currently having severe or widespread negative impacts on wildlife or natural communities in Louisiana.” It is now found throughout the U.S.

AlterNATIVE choices: LOUISIANA IRIS

Benefits The series Hexagona holds the five species of Louisiana Iris, so named for the unique six-sided seed capsule and their greatest profusion in Louisiana. New Orleans was once called the “Iris Capital of the World.”

These are perennial, rhizomatous iris with no midrib in the leaf. Most species grow from Texas to North Carolina, up the Mississippi River valley to Ohio and Indiana.

Water is essential for their growth and distribution. Today, destruction of natural wet areas and invasive species are the foremost threats to wild populations.

There are many hybrids and variants with differing garden characteristics based on the five parent plant species. All are dormant in summer, start growth in fall and bloom in spring. Rhizomes need dividing every 2–3 years. The vibrant clumps of upright green leaves enliven the gray winter landscape.

IRIS BREVICAULIS, ZIG-ZAG IRIS

• This is the shortest (both in leaf and stalk) iris in the Louisiana series. The stalk is erect to sprawling, 10-14", and has a distinct zig-zag form.

• The large showy flowers with dark veining can have the deepest blue of all; blooms are below foliage height.

• The most widely distributed Louisiana iris, found on wet sites from prairies to marshes to bottomlands, with the greatest adaptation to cold and more upland areas.

IRIS FULVA, COPPER IRIS

• This iris is easily known by its unusual, for an iris, reddish color and flaring to drooping petals that give it a flat-top look. Fulva is Latin for tawny color.

• The blooms are 3–5" wide atop a slender, rarely branching, light green stem, with narrow, light green basal leaves.

• First “discovered” in 1811 near New Orleans, it caused a sensation in the western plant world due to its red color and possibilities for hybridization.

• Found in freshwater only, in wet woods, sloughs and ditches.

IRIS NELSONII, ABBEVILLE IRIS

• Similar to the Fulva but taller and with more intense color, often with a branched stalk. It is of natural hybrid origin from Fulva, giganticaerulea and brevicaulis.

• Found naturally only in a small area of tidally influenced, freshwater swamp south of Abbeville, Louisiana. It has been planted at Palmetto State Park in Vermillion Parish and also at City Park Native Plant Trail in New Orleans.

IRIS GIGANTICAERULEA, GIANT BLUE IRIS

• The largest and tallest species in the series, the pale to deep blue or white bloom is 5-6" wide, double flowered at terminal position above leaves with all others single on the strong, unbranched stalk. The three wide sepals arch down and typically have a yellow signal. The three smaller, narrower petals are erect. Narrow, tall, sword-like basal leaves.

• Suited to gardens only if in or at edge of water. Stately and impressively lovely.

IRIS HEXAGONA, DIXIE IRIS

Photos courtesy of ©Larry Allain, U. S. Geological Survey

• Similar to the Giant Blue but a little smaller; there is dispute as to it being a separate species or a variant.

• Not in the Hexagona or Louisiana series, but alternative to Dutch Iris also: Iris virginica– Southern Blue Flag.

• Found mainly in shallow water of Louisiana coastal areas to about 100 miles inland in marshes, ponds and open swamps. Thrives under flood and tolerates brackish water to some extent.