Swap Invasive Plant Pests for Well-Behaved Plant Pals

Blazing star (Liatris ligulistylis)

By Debra Knapke

PART TWO: The Alternatives

Here are some “poster children” of the invasive plant world. Each is followed by a few well-behaved alternatives.  According to C. Colston Burrell, author of Native Alternatives to Invasive Plants, “The best alternative is one that mimics some desired characteristic of the invasive plant, such as flower or fruit color.”

Be sure to check that the alternatives are suitable for your area and soil conditions.

Trees and Shrubs

Autumn-olive, Russian olive – (Elaeagnus umbellata, E. angustifolia), introduced in the late 1800’s as ornamentals.

strawberry bush (Euonymus americanus), wax-myrtle, bayberry (Morella cerifera, M. pensylvanica), viburnums (Viburnum prunifolium, V. lentago), shrub dogwoods (Cornus racemosa, C. amomum), pawpaw (Asimina triloba), serviceberries (Amelanchier spp.)

Common buckthorn, European buckthorn – (Rhamnus cathartica, R. frangula)

winterberry (Ilex verticillata), dogwoods, spicebush (Lindera benzoin), white cedar (Thuja occidentalis)

Japanese barberry (Berberis thunbergii); listed as invasive in 20 states; still used in the landscape.

chokeberries (Aronia), common ninebark (Physocarpus opulifolius), weigela (Weigela floribunda cultivars), winterberry holly (Ilex verticillata)

Non-native shrub honeysuckles – (Lonicera maackii, L. morrowii, L. tatarica), etc., imported as ornamentals and for soil erosion control, group listed as invasive in 46 states; some are still used in the landscape.

shrub dogwoods, spicebush, sweetshrub (Calycanthus floridus)

Grasses and Perennials

Common reed grass – Phragmites australis, hard to distinguish from native species; probably crossed with US native strains.

Spike Gayfeather (Liatris spicata)

Indian grass (Sorghastrum nutans), big bluestem (Andropogon gerardii), and prairie cordgrass (Spartina pectinata)

Purple loosestrife – (Lythrum salicaria and its hybrids), ornamental introduced in early 1800s.

swamp milkweed, (Asclepias incarnata), purple coneflowers (Echinacea spp.), blazing stars (Liatris spicata, L. pilosa, L. ligulistylis)

Aquatic Plants

Water hyacinth – (Eichornia crassipes), introduced as an ornamental; fortunately not hardy in most of the Midwest

yellow water lily, American white waterlily (Nymphaea mexicana, N. odorata), pickerelweed (Pontederia cordata)

Vines and Groundcovers

Japanese wisteria – (Wisteria floribunda), listed as invasive in the Northeast, Mid-Atlantic and the Southeast US; the Midwest will probably soon follow.

American wisteria (Wisteria frutescens), Kentucky wisteria (W. macrostachya).

Porcelainberry – (Ampelopsis brevipedunculata), ornamental introduced in the 1870s, still used in the landscape; listed as invasive in 12 states.

leatherflower (Clematis viorna), Carolina jasmine (Gelsemium sempervirens), Virginia creeper (Parthenocissus quinquefolia), wild honeysuckle (Lonicera dioica), and virgin’s bower (Clematis virginiana)

Wintercreeper euonymus – (Euonymus fortunei), ornamental introduced in 1907; still used in the landscape. Select alternative based on intended use as groundcover or vine.

bearberry (Arctostaphylos uva-ursi),trumpet creeper (Campsis radicans), crossvine (Bignonia capreolata), trumpet honeysuckle (Lonicera sempervirens), American bittersweet (Celastrus scandens), and American wisteria (Wisteria frutescens).

Note: US natives trumpet creeper, crossvine and American bittersweet are veryvigorous vines.

Previously published in the Garden Writers Association Quill & Trowel No. 3, June 2012.

Swap Invasive Plant Pest for Well-Behaved Plant Pals

Purple loosestrife

By Debra Knapke

Invasive species are a part of the fabric of the world.  Well-mannered plants and animals in one country become thugs in another country or region for a variety of reasons.  What follows is part of my report that appeared in the Garden Writers Association Quill and Trowel June newsletter.   I’ve split the article into two parts because of the length of the original article.  The second part, which presents invasive plant substitutes, will follow next week.

PART ONE:  Invasives – the basics

Invasive is a word that many use to describe the plants that overrun our constructed and natural landscapes. Plants, by their nature, multiply in order to ensure their survival as a species. But what is the difference between a vigorous groundcover or colonizing shrub and an invasive plant?

Invasive plants are characterized by several traits:

• fast growing
• adaptable to a wide range of conditions,
• deeply and firmly rooted,
• allelopathic action on other plants,
• make thousands of seeds that are easily dispersed,
• grow from a tiny piece of root,
• difficult to kill, and most importantly,
• out-compete other plants and degrade native habitat.

Unfortunately, many plants have been called invasive that really belong more in the “this is a pain to get rid of, but it can be done” category. Think of mint (Mentha spp.) or sweet woodruff (Galium odoratum). Yes, they spread, but they are shallowly rooted and can be edited from a garden quite easily. The three most significant traits of invasive plants are competitiveness, habitat degradation, and difficult-to-kill. Think purple loosestrife, wintercreeper euonymus, or water hyacinth.

Fighting the spread of invasive plants is an ongoing task not only for gardeners, but also for state, federal, and international agencies and conservation groups. While eradication of invasive plants and restoration of ravaged habitats is the primary goal of these groups, the critical first step is “knowing the enemy”.

Loosestrife escapes along railroad tracks

It isn’t feasible here to mention all of the plants that are listed as invasive in the Midwest, but it is important to understand that invasive can be a regional concept.  A plant that is invasive in Georgia (e.g. Japanese bloodgrass, or kudzu) may not be invasive in the colder areas of the Midwest.

Information is easy to find

Consult local conservation groups, botanic gardens or your state Division of Natural Resources to find out which plants are on the invasive list and which are on the watch list. As C. Colston Burrell, author of Native Alternatives to Invasive Plants states, “We really need to take a hard look at some of the potentially invasive plants that we are now using as ornamental plants, such as Chinese elm and Bradford pear, that are showing up in native ecosystems as adult flowering and seeding plants.”

The ongoing effort to eradicate invasive plants might be compared to the labors of Sisyphus. The bottom line: do not purchase invasive plants, remove them if they are already planted, and choose wisely when creating the garden of your dreams.  Part Two is a short list of invasive plants and some alternatives.

References: (a place to start)

National Invasive Information Center

National Park Service, Alien Plant Invaders of Natural Areas: Fact Sheet

Ohio Invasive Plants Council Fact Sheets

Invasive Plant Finder — Remember: invasiveness is often a regional issue

Lady Bird Johnson Wildflower Center

Excerpted from an article published in the Garden Writers Association Quill & Trowel No. 3, June 2012.