The spring landscape is covered with the tell-tale pale green. Spring flowering trees – such as the redbud with their pink flowers, dogwoods with either white or pink blossoms that appear to be floating on branches and lilacs with their purple plumes of flowers – waft sweet fragrance through the air.

The spring landscape is covered with the tell-tale pale green. Spring flowering trees – such as the redbud with their pink flowers, dogwoods with either white or pink blossoms that appear to be floating on branches and lilacs with their purple plumes of flowers – waft sweet fragrance through the air.

Spring is also the time to further develop or begin a landscape plan. Most people have no idea how important it is to be familiar with the plants they are choosing to place in their yards and gardens. While many are beautiful and so tempting to have, some plants can have potentially devastating results to nearby woodlands, fields and streams. Therefore, it is critical to know all of the ramifications of trees, shrubs and herbaceous plants before placing them in the landscape.

Once again, the importance for native species can be emphasized here because native species (plants from the geographic area) do not get out of control and do not become invasive. Alan Branhagen, director of horticulture at Powell Gardens, Kansas City’s Botanical Gardens, detailed a comprehensive list of plants that should be used with care when placed in a landscape. Some of these even surprised me.

Invasive species typically travel one of two ways, either by seed or by root. If they travel by seed, it is often by birds. The birds eat the fruit (with the seed inside) or they eat the seeds themselves. As the birds sit on fence rows or in trees, they poop the seeds out and start new generations of the plants. Count the number of fruits or seeds on one plant and think of the number of seeds that can be dispersed all over the area by birds. When those plants grow, in a year they’re blooming and making seeds. You see how fast and out of control this can get.

Some seeds can also spread by catching on animal fur. The seed head typically has barbs or hooks, and when the animal walks by, the seed head sticks to the fur until it gets brushed off or scratched off at another site. The plant can also simply self-sow, producing so many seeds they just simply have to fall below the seed head and grow huge patches. This is how Teasel (Dipsacum laciniata), a very invasive biennial, spreads. Teasel is most often seen along the highway, especially near entrance and exit ramps and bridges where it is hard to mow. The seed head is ornamental and used heavily for dried flower arrangements, but it generates copious amounts of seeds. It is actually on the noxious weed list and is very invasive.

Seeds travel in other ways, but for invasive species, these are the main modes.

Homeowners are not the only ones that have been the culprits of spreading invasive species. Indeed, the Conservation and Transportation departments have been guilty of this, too. The Missouri Department of Conservation planted multi-flora rose and autumn olive decades ago, thinking they would provide good wildlife food and habitat. It wasn’t until years later that they discovered that both of these plants were fast becoming invasive all over the state.

The Missouri Department of Transportation planted crown vetch along steep highway embankments, entrance and exit ramps and other places for erosion control. Again, this plant quickly showed its invasive nature and is banned from all use.

These examples show the importance of continued study on the effects the plants we have chosen to introduce into our landscape are having on the natural landscape around us. It is naïve of us to think our actions have no impact on the surrounding environment. Our gardens and landscapes can be beautiful reflections of us, our taste and our sanctuaries for relaxation, but they also come with responsibility.

Below is Alan Branhagan’s list of invasive species. Plants are coded into the following categories:

1. Plants that are currently severe pests and whose seeds are dispersed far and wide by birds (droppings) or animals (many get transported in a deer’s fur). These plants should not be planted, and all existing plants should be removed.

2. Plants that are severe pests near where planted but whose seeds do not disperse great distances. These plants should not be planted near natural lands.

3. Plants that are severe pests in certain parts of the Midwest and should be monitored for invasiveness. Use is discouraged near nature preserves.

Woody plants:

2. Amur maple Acer ginnala: (small tree)

3. Norway maple Acer platanoides

2. Tree-of-Heaven Ailanthus altissima

3. European alder Alnus glutinosa

1/3. Porcelainberry Ampelopsis brevipedunculata and cultivars

3. Japanese barberry Berberis thunbergii and cultivars: (shrub)

1. Paper mulberry Broussonetia papyrifera: (small tree)

1. Oriental bittersweet Celastrus orbiculatus: (woody vine), known as the kudzu of the north. Alternate: American bittersweet Celastrus scandens

2. Sweet autumn clematis Clematis terniflora/ C. paniculata

1. Autumn-olive Elaeagnus umbellatus

2. Burning bush Euonymus alata

1. Winterberry euonymus Euonymus fortunei

2/3. Goldenrain tree Koelreuteria paniculata

1. Japanese honeysuckle Lonicera japonica and cultivars ‘Hall’s’, ‘Purpurea’, ‘Reticulata’...: (evergreen woody vine) This popular vine is a noxious weed. Birds spread it far and wide. It is banned in Illinois.

1. Amur honeysuckle Lonicera maackii: (bush honeysuckle)

1. White mulberry Morus alba:

3. Privets Ligustrum spp. In the South, the Chinese privet Ligustrum sinense is a horrific pest to woodlands. This plant is supposedly hardy only in Zone 7, but there are several big shrubs of its variegated cultivar growing in the Kansas City area.

2. Boston ivy Parthenocissus tricuspidata

1. Bradford pear and Callery pear Pyrus calleriana including all cultivars ‘Bradford’, ‘Aristocrat,’ ‘Autumn Blaze,’ ‘Chanticleer’ and others.

3. European buckthorn Rhamnus cathartica: (small tree)

3. Glossy buckthorn Rhamnus frangula:(large shrub, small tree)

1. Multiflora rose Rosa multiflora: (large shrub)

2. Siberian “Chinese” elm Ulmus pumila: (shade tree)

2 True Chinese or lacebark elm Ulmus parvifolia: (shade tree)

3. Viburnums Viburnum spp.

3. Other plants:

Hardy mimosa Albizzia julibrissin var. rosea;

Butterflybush Buddleia davidii

Purple beautyberry Callicarpa dichotoma

Rose-of-Sharon Hibiscus syriacus

Pyracantha Pyracantha species and hybrids.

Semi-woody plants

1. Sericea Lespedeza sericea

1/2. Japanese bush-clover Lespedeza thunbergii

Herbaceous plants: Many, many species of exotic herbaceous plants have escaped in our region and have become the dominant flora in most landscapes. Most do not seem to usurp native plants, but a few are displacing native plants and habitats. Their seed is often spread by lodging in the pelts of deer and other animals.

1. Nodding thistle: there are numerous native thistles that are not invasive.

1. Bull thistle Cirsium vulgare

2. Crown vetch Coronilla varia

1. Greek foxglove Digitalis ferruginea (this is not the English foxglove!)

1. Teasels Dipsacum laciniata and other similar species

1. Tall fescue Festuca arundinacea

2. Yellow flag iris Iris pseudacorus

2. Perennial sweet pea Lathyrus perennis

2. Bird’sfoot trefoil Lotus corniculatus

1. Purple loosestrife Lythrum salicaria

2. Eulalia grass, maiden grass or just “miscanthus” Miscanthus sinensis

3. “Pampas” grass Miscanthus sacchariflorus

1. Wild parsnip Pastinaca sativa

2/1. Black fountain grass Pennisetum alopecurroides  

Grass Phalaris arundinacea non-native strain

Verbena bonariensis – must have disturbed soil to self-sow, it is quickly displaced by perennial plants in natural settings.

Cleome Cleome spp. – this annual is wildly invasive in garden or disturbed soil areas

Gooseneck loosestrife Lysimachia clethroides

Chameleon plant Houttuynia cordata

For more information on Branhagan’s Invasive Plants and suggested alternative plants check out: