The Ecological Regions of Kentucky

Kentucky is a state rich in natural beauty and diversity, with a range of ecological regions that support a wide variety of plant and animal species.

Because of this diversity, it's important to know the ecological region you live in when selecting native plants for your garden. Otherwise, you might be choosing plants that aren't necessarily adapted to where you live.

In this article, we'll explore the five ecological regions of Kentucky, and the counties within them, so you can confidently select native plants that are well-suited for your local environment.

Drop-downs are available in each section to view individual county names.

Let's get started.

Disclaimer:

The diagrams used in this article are simplified, using county lines as regional borders. The actual borders of ecological regions may vary. For an accurate map and accompanying information, please view the University of Kentucky’s Kentucky geological survey.

What Are Ecological Regions?

Ecological regions, or ecoregions, are large areas of land and water that share similar physical and biological characteristics, such as climate, soil, vegetation, and wildlife. They are used to study and understand the relationships between plants, animals, and the environment, and to help guide conservation efforts.

Ecological Regions of Kentucky

There are five main ecological regions of Kentucky: the Bluegrass, the Mississippian Plateau, the Shawnee Hills, the Jackson Purchase, and the Appalachian Plateaus.

Some of these regions can be further divided into sub-regions. For instance, the Bluegrass contains the Inner Bluegrass, the Outer Bluegrass, and The Knobs, while the Appalachian Plateaus contain the Cumberland Mountains.

1. Bluegrass Region

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The Bluegrass Region is located in north-central Kentucky and contains cities like Louisville, Lexington, and Covington. Its name comes from a European grass species that was introduced to Kentucky.

The area is known for its fertile soils, which are enriched with minerals from the abundance of limestone found in the area. This limestone also tends to result in a basic soil pH in parts of the region, making it ideal for certain plants.

Historically, the Bluegrass was an open-savanna ecosystem with large trees scattered over an understory of grassland. After pioneers arrived, almost every acre in the region was converted to farm land, erasing the natural landscape.

Some notable plants native to the Bluegrass region are New England Aster (Aster novae-angilae), Running Buffalo Clover (Trifolium stoloniferum), Bur Oak (Quercus macrocarpa), Kentucky Coffeetree (Gymnocladus dioicus), and Blue Ash (Fraxinus quadrangulata).

The Bluegrass region can be broken down into three sub-regions: the Inner Bluegrass, the Outer Bluegrass, and The Knobs, which we'll cover before getting into the next major region.

Inner Bluegrass

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The Inner Bluegrass is located in the heart of the Bluegrass Region and contains cities like Lexington, Georgetown, and Nicholasville.

The region is known for its gently rolling hills and relatively flat land, compared to the rest of the Bluegrass, which came from the slow weathering of its thick limestone bedrock. These conditions, and its fertile soil, have created the perfect conditions for horse breeding, which the region is famous for.

Some notable plants native to the Inner Bluegrass are Kentucky Clover (Trifolium kentuckiense), Soft Fox Sedge (Carex conjuncta), Rock Elm (Ulmus thomasii), and Snow Trillium (Trillium nivale).

Outer Bluegrass

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The Outer Bluegrass surrounds the Inner Bluegrass, and makes up the majority of the greater Bluegrass Region. It contains cities like Louisville, Covington, and Florence.

The Outer Bluegrass is similar to the Inner Bluegrass, but is less flat and features deeper valleys. This is due to a mixed bedrock of shale and limestone, which makes it more erosion-prone compared to the Inner Bluegrass's thick limestone bedrock

Some notable plants native to the Outer Bluegrass are Green Milkweed (Asclepias viridis), Pussy Willow (Salix discolor), Canadian Goldenrod (Solidago Canadensis), and Short's Goldenrod (Solidago shortii).

The Knobs

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The Knobs region borders the Outer Bluegrass and contains cities like Richmond, Berea, and Danville. Bernheim Forest is also found here.

The region gets its name from the hundreds of steep-sloping, cone-shaped hills found in the area, commonly known as knobs. Deep, rich soil has accumulated in the valleys between the hills, creating valuable farm land.

Some notable plants native to The Knobs are Wild Pink (Silene caroliniana), Pale Spiked Lobelia (Lobelia spicata), and Smooth Aster (Symphyotrichum laeve).

2. Mississippian Plateau Region

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The Mississippian Plateau, also known as the Pennyroyal or Pennyrile Region, is located in south-central and western Kentucky. It contains cities like Bowling Green, Elizabethtown, and Hopkinsville. The name Pennyroyal comes from a European mint-like plant introduced to the area.

The region is a limestone plain that groundwater has slowly eroded over time, creating thousands of caverns, springs, disappearing streams, and sink holes. Its deep, rich soil has made it a hub for agricultural farming, which has greatly diminished the large areas of prairie it historically contained.

Some notable plants native to the Mississippian Plateau Region are Pale Purple Conerflower (Echinacea pallida), White Prairie Clover (Dalea candidum), Switchgrass (Panicum virgatum), Little Bluestem (Schizachyrium scoparium), and Buffalo Clover (Trifolium reflexum).

3. Shawnee Hills Region

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The Shawnee Hills Region, also known as the Western Coal Fields, is located in north-western Kentucky and contains cities like Owensboro, Henderson, and Madisonville. Green River and Mammoth Cave National Park are also found in the region.

The region is made up of swampy areas along the flood plains of the Green River and oak-hickory forests dispersed through the low hills found upland. The swampy areas typically have acidic, infertile soil while the upland areas commonly have more fertility from sediment blown in from the wind. Mammoth Cave National Park is the only national park found in Kentucky, so the region is quite special.

Some notable plants native to the Shawnee Hills Region are the Pecan Tree (Carya illinoinensis), Overcup Oak (Quercus lyrata), and Water Hickory (Carya aquatica).

4. Jackson Purchase Region

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The Jackson Purchase Region, also known as the Mississippi Embayment, is located on the western edge of Kentucky along the Mississippi River. It contains cities like Paducah, Murray, and Mayfield.

The region is relatively flat, with low plains, and is a major wetland area unique to Kentucky. It contains several ponds, river bottoms, sloughs, and swamps. It also contains the lowest elevation of the state, at only 260 ft above sea level. The soils are formed of clays and sands deposited from past flooding.

Like many of our regions, it's been largely cleared for human development, leaving little of what was originally there. However, a small wetland area remains protected in Hickman County, named Murphy's Pond, that's owned and managed by Murray State University.

Some notable plants native to the region are the Pecan Tree (Carya illinoinensis), Bluestar (Amsonia tabernaemontana), Bald Cypress (Taxodium distichum), Willow Oak (Quercus phellos), and Blue Jasmine (Clematis crispa).

5. Appalachian Plateaus Region

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The Appalachian Plateaus, also known as the Eastern Coal Fields Region, makes up the majority of eastern Kentucky, and contains cities like Ashland, Middlesboro, and London. The region also contains some of the most scenic areas of Kentucky, such as Red River Gorge, Cumberland Falls, and Natural Bridge.

The region is known for its rugged terrain of cliffs, steeply sloping ravines, and narrow valley bottoms. The soils here are slightly acidic from an abundance of sandstone and shale, but neutral pH soils can also be found from pockets of limestone. This assortment of pH allows for a wide diversity of native plants to be found.

Historically, the region was a mixed forest with a vast diversity of trees, but between the heavy logging practices of the 1800's, and the chestnut blight of the early 1900's, little is left of what was originally there.

Some notable plants native to the region are Mountain Stewartia (Stewartia ovata), Eastern White Pine (Pinus strobus), Upland Highbush Blueberry (Vaccinium simulatum), Dwarf Ginseng (Panax trifolius), and Creeping Phlox (Phlox stolonifera).

Cumberland Mountains

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The Cumberland Mountains Region is located at the south-eastern edge of the Appalachian Plateaus, and contains cities like Middlesboro, Cumberland, and Harlan. Kentucky's highest elevation is found here, at Big Black Mountain, which sits at 4,145 ft above sea level.

The region's steep mountains allow for shading and pockets of cool, moist habitat. This, and the high elevation allows for plant communities unique to the region. Soils here are generally rich and slightly acidic. In the past, the Cumberland Mountains were part of some of the most diverse forests of the Eastern US. Unfortunately, it was also heavily logged and impacted by the chestnut blight epidemic like the rest of the Appalachian Plateaus.

Some notable plants native to the Cumberland Mountains are Painted Trillium (Trillium undulatum), Mountain Holly (Ilex montana), Dwarf Chinkapin Oak (Quercus prinoides), and Striped Maple (Acer pensylvanicum).

Preserving Our Ecological Regions

Kentucky is home to a variety of ecological regions, each with its own distinct characteristics and species of plants. By understanding and protecting the ecological region you live in, we can ensure a healthy and thriving natural environment for all the species that call this state home.

Make sure to check for your region in the "Native Range" section of the plant infographics we include in every plant list article. It will help you select the ones that are well-suited for your local environment. Leave a comment with what ecological region you're from!