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Oklahoma's Dirty Dozen
In the early 1900s, Yellow Bluestem was introduced from Southern Europe and Asia for livestock forage and erosion
control. Today, this exotic grass is prevalent throughout the state, altering soil conditions and microorganisms as well
as suppressing important native grasses with the end result of decreasing the diversity of native animal communities.
Over the past 60 years, Field Brome has been outcompeting desirable vegetation for water and soil
nutrients, inevitably decreasing biodiversity in native ecosystems. Field brome was originally introduced from Eurasia for
the purpose of erosion control and use as a cover crop. This species is now scattered throughout Oklahoma, with the
exception of the northeast corner.
Cheatgrass is not only spreading across Oklahoma, but all of North America as well. It was
originally introduced when used as a transport packing material from the Mediterranean region of Europe. This aggressive
species is notorious for forming monocultures and completely displacing native species as well as decreasing crop production.
Musk/Nodding Thistle was accidentally introduced, possibly through ballast water or as seed
contaminant in the late 1800's. It is mainly found in the north half of the state, east of Woodward, and scattered
throughout south central and extreme southeast Oklahoma. Musk/Nodding Thistle is a listed noxious weed in Oklahoma, due to its
ability to crowd out native vegetation and forage for livestock and wildlife.
Eastern Redcedar has become a common evergreen woody species found across the state. Even though
this species is native to parts of Oklahoma, fire suppression and planting as shelterbelts and to screen visibility, has
allowed Eastern Redcedar to dominate habitats where it should not be found. Dense stands of cedar force out native grass
and woody species, decreasing biodiversity and increasing fuel loads which increase the risk of wildfire.
In 1899, Sericea lespedeza, a native to China and Japan, was planted for erosion control and as
an additional food source for Bobwhite Quail. It has now spread throughout the state, except the panhandle, proven to not
be a good food source for Bobwhite quail, and is rapidly outcompeting and displacing native herbaceous and woody species,
destroying habitat quality for wildlife and forage production for livestock.
The Chinese Privet was brought from China as an ornamental shrub, but was discovered to form
dense thickets, shading out native species of the understory. This exotic plant can now be found in the eastern third of
Oklahoma and scattered in the southwest part of the state.
Japanese Honeysuckle was imported for deer browse, erosion control, and as an ornamental in the
early 1800's. Today, this evergreen vine from Japan inhabits the eastern half of the state as well as Jackson, Caddo,
Comanche, Grady, and Ellis counties, overtaking native herbaceous and woody vegetation.
In the 1870's, the prickly Russian Thistle was accidentally introduced from Eurasia as a seed
contaminant in flax seed. This species becomes the tumbleweed that clog fence lines and host leafhopper species which
carry Curly Top virus in multiple crop species. It is now found in the western half of the state and panhandle, as well
as Bryan and Muskogee counties.
Johnsongrass was popularized as livestock forage and for hay production, but under certain
conditions it can actually become toxic to livestock. It was introduced from the Mediterranean region around the 1830's,
and has now spread across the entire state of Oklahoma. It invades all stages of rangeland succession, reducing
biodiversity and habitats for many species of wildlife.
Saltcedar is an eastern Asian shrub that was brought in as an ornamental and for erosion
control. Originally introduced in 1823, Saltcedar has now spread statewide altering stream flow and overtaking many food
producing plants for wildlife as well as other native wetland and floodplain plants that wildlife depend on for habitat.
Siberian Elm is native to China, Siberia, and Turkestan but was brought to America in the 1860's
as a replacement for the American Elm after the breakout of Dutch Elm disease. It is now found to alter wildlife habitat
and impact native floodplain vegetation water usage. Today, Siberian Elm can be found in Woods, Woodward, Alfalfa,
Cleveland, and Mayes counties.
Source: Oklahoma Invasive Plant Council
photos by Louise C. Basham
Wild About Piedmont
Piedmont's Community Wildlife Habitat Project
phone: 405-202-3984 - email: email@example.com