Promoting alternatives to invasive landscape plants
Each year Bernheim Arboretum and Research Forest, the Southeast Exotic Pest Plant Council and the Environmental Resource Management Center at Northern Kentucky University publishes a poster of those plants that have proven to be invasive of our native habitats. These introduced plants are out-competing our native species resulting in a reduction of plant diversity. We urge everyone to be on the lookout for these plants and avoid planting them in your yards. Instead, we offer similar native plants that can and do provide similar enhancements to your environment.
Bernheim Arboretum |
Environmental Resource
Management Center, |
Good Native Alternatives
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Blazing star Liatris spicata A showy alternative to Purple loosestrife, Blazing star flowers in the late summer and can reach heights up to 3 ft. Blazing star grows in wet, open areas, but it adapts easily to typical garden soil conditions. The flowers of blazing star attract a wide variety of butterflies. Some excellent cultivars include, Floristan White, and Floristan Violet. |
Great blue lobelia Lobelia siphilitica This striking plant is native to moist, shaded, woods, however, it can tolerate full sun in a garden. The plant grows 1-3 feet tall and produces spikes of blueish lavender flowers throughout the month of September. White-flowered individuals of this species are sometimes found. Blue lobelia is easily propagated by division or seed.
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Obedient plant Physostegia virginiana Obedient plant is a reliable late summer bloomer for the perennial border. Obedient plant was named because the flowers can be twisted on the stem and remain as arranged. Best in full sun, the plant also will perform admirably in light shade. Vivid, Variegata, and Miss Manners are excellent cultivar selections.
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2002 Least Wanted!
Euonymus fortunei
Wintercreeper was introduced to the U.S.
from China in the early 1900s as a landscape plant. Popular as a ground
cover because of its rapid growth and ability to tolerate a wide range of
growing conditions, this species has become a threat to natural areas.
Wintercreeper spreads aggressively by lateral shoots; however, birds that feed on the fruits can carry the seed great distances. This species invades both disturbed and undisturbed forests, and once established it outcompetes the native understory vegetation. We are requesting the help of nursery owners, landscapers and gardeners to prevent further spread of this species by not using it in gardens. Several alternatives are presented below.
Good Native Alternatives
Ginger - Asarum spp.
Wild ginger, Asarum canadense, is native to Kentucky and can form a beautiful ground cover, It is a deciduous spreader with flat green leaves that spreads rather slowly. Asarum europeum, an introduced species, forms a deep glossy evergreen ground cover and has not been found to be invasive. Asarum shuttleworthii, native to the southeast U.S. is a finer textured, evergreen clumping form, excellent for use in small garden areas. Most gingers grow best in moist, shady, slightly acid soils.
Allegheny Spurge - Pachysandra procumbens
Allegheny spurge is another native Kentucky species that forms a ground cover in shady conditions. Meadium green leaves are mottled with white veins and are evergreen in warmer winters. Allegheny spurge will not produce a ground cover as quickly as Wintercreeper; however, this very attractive and underused species is worth the wait.
Mountain Lover or Cliff Green - Paxistima canbyi
This Kentucky native is rare, but is now becomming more available through nurseries. A very fine-textured, low-growing, evergreen shrub, to about 12" tall, Mountain lover is appropriate for a ground cover in smaller areas as it is slower to establish. Mountain lover is found in dry, rocky woods in light shade.
2003 Least Wanted!
Crown vetch - Coronilla varia
photo copyright John M. Randall - The Nature Conservancy
Crown vetch is native to Europe, southwest Asia and northern Africa. This perennial herb forms a groundcover in open, sunny conditions and has been planted extensively along disturbed roadsides as a soil stabilizer. Crown vetch spreads by seed and by a creeping root system. Once Crown vetch becomes established, it outcompetes the native understory vegetation: it has become a serious threat to native grasslands and open woodlands. We are requesting the help of nursery owners, landscapers and gardeners to prevent further spread of this species by not using this species in gardens. An alternative is presented below.
Good Native Alternative
Prairie mix
photo by Dave Imbrogno
The sunny, rocky sites where Crown vetch is often planted are ideal areas to plant a drought-tolerant low-growing mix of prairie species. Prairie species like Little bluestem (Schizacharium scoparium), Prairie dropsed (Sporobolis heterolepis), Indian grass (Sorghastrum nutans), Purple coneflower (Echinacea purpurea), Rough blazing star (Liatris aspera),and Gray goldenrod (Solidago nemoralis) are just a few of the plants that will thrive in dry, open sites.
Replacing Crown vetch with prairie species will increase the native diversity of the site, and will also increase the colorful displays of flowers throughout the growing season. Birds will be attracted to the many seeds produced by the prairie planting, adding even more beauty and diversity to the site.
Prairie species are easily grown from seed, however, they typically take a year to become established. It is important to add a rapidly establishing annual plant, like annual wheat or annual rye to the mix to help hold the soil during the first year after planting.
2004 Least Wanted!
Burning Bush - Euonymus alatus
Burning Bush's bright red fall foliage and hardy nature have made it a very popular landscaping shrub. Unfortunately, this shrub's broad habitat tolerance and dispersal by birds make the species a threat to Kentucky's natural areas. Once Burning Bush becomes established into a natural area, it rapidly dominates the understory, outcompeting the native vegetation.
Good Native Alternatives
Strawberry Bush - Euonymus americanus
This deciduous shrub grows 6-12 ft. tall. Its pale green flowers produced in May-June have a sweet fragrance; however it is the pink and orange fruits produced by this shrub in October-November that are its greatest appeal. Strawberry bush, also know as Hearts a Bursting with Love, thrives in well-drained loamy soil and light shade. This shrub is not a good selection in locations where deer browse is a problem, this species is a favorite of deer.
Spice Bush - Lindera benzoin
Spicebush is a natural alternative to Burning Bush because it is shade-tolerant and produces attractive red berries in the fall. Clusters of yellow flowers appear in March before the leaves develop. Although the flowers are not fragrant, the leaves, twigs and berries give off a spicy aroma when crushed. This native of Kentucky is frequent in moist woods throughout the state and grows well in rich moist soil.
Winterberry Holly - Ilex verticillata
Winterberry Holly is a multistemmed deciduous shrub known for its exceptionally showy bright red fruit in fall and winter. Native through the eastern coast of North America and sporadically through the midwest, this 5 to 10 shrub is an excellent choice for full sun in both low/wet and upland soils. There are many cultivars available including compact growers, orange and yellow-fruited forms. Plant both male and female forms for best fruit production on the females.
2005 Kentucky's Least Wanted Plant
Promoting alternatives to invasive landscape plants
Each year Bernheim Arboretum and Research Forest, the Southeast Exotic Pest Plant Council and the Environmental Resource Management Center at Northern Kentucky University publishes a poster of those plants that have proven to be invasive of our native habitats. These introduced plants are out-competing our native species resulting in a reduction of plant diversity. We urge everyone to be on the lookout for these plants and avoid planting them in your yards. Instead, we offer similar native plants that can and do provide similar enhancements to your environment.
Least Wanted!
Chinese Silver Grass - Miscanthus sinensis
Miscanthus is a tall ornamental grass that grows in clumps and has feathery seed tops. Its long, slender, arching leaves and stems make it popular as a landscape plant. However, the seeds can blow great distances and become established in thin, disturbed soils, especially along roadsides, in power line rights-of-way, and along forest margins in the southeast and mid-Atlantic states. Once established, it can grow aggressively and out-compete native grasses and wildflowers.
Good Alternatives
Miscanthus X giganteus or Miscanthus 'Purpurascens'
Not all Miscanthus species are invasive. These hybrid forms have infertile seeds that rarely reproduce. They have the same height and structure as M. sinensis and are attractive alternatives. M. 'Purpurascens' leaves turn a beautiful red-orange in fall and M. giganteus has a yellow fall color.
Miscanthus sinensis var. gracillimus
This is another noninvasive, sterile form with nearly the same height as the invasive species. Leaves reach up to 6' and flower spikes up to 8'. Leaves on this variety are less than 1/4 inch wide and are green. Flower spikes are shimmery silvery-red and fade to silvery. Dead foliage turns tan and will remain in place all winter. Plant with room to expand as plants form large clumps.
Good Native Alternatives
Switch Grass - Panicum virgatum
photo
courtesy of Richard Darke
Also known as tall panic grass, this is a tall, warm season, vigorous perennial native to Kentucky. It has green blades as leaves with a reddish tint. Blades can be up to 5' tall. Panicles of small reddish flowers are borne on the ends of long stems from June to August. In the fall, switch grass blades turn yellow and the seeds on the panicles turn beige. Switch grass grows best in full sun and in wet-moist soils. Switch grass is best used in the back border of a perennial bed or in a wildflower meadow. Birds and small mammals use switch grass as a food source, Many songbirds use the leaves and stems as nest materials.
Indian Grass - Sorghastrum nutans
photo
courtesy of Richard Darke
This warm season perennial bunch grass is native to Kentucky. It grows from 3'-7' in height. Indian grass has long, flat, narrow leaf blades that become yellowish bronze in the fall. Dense bronze-yellow flowers occur in narrow, oblong panicles in August and September. It has yellow spikelets (seed heads) that have white hairs that make it look gold and silver in the sunlight. Indian grass grows best in full sun and is fairly tolerant of drought conditions. It is best used in the back border of a perennial bed or in a wildflower meadow. Indian grass is a host plant for skipper butterflies. Birds and small mammals eat the seeds.
2006
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