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No doubt many of you have heard about invasive species and the havoc they can wreak on our local ecosystems. As for plants, Bohemian (aka Japanese) knotweed, orange hawkweed and oxeye daisy are among some of the most commonly known and found in Southeast Alaska.

If you have them in your yard, you are probably all too familiar with how difficult these hardy, competitive, aggressive reproducers are to eradicate. Many of our invasive weeds were brought to Southeast by gardeners who enjoyed their beauty and the extra benefit of being easy to care for. Discussed here are a few of the lesser-known and most beautiful invasive weeds that continue to be found in Juneau gardens.

These plants truly are beautiful. Brilliant shades of pinks and purples. Stalks of uniquely shaped bell flowers. Their presence is dramatic. It's hard to tell a gardener that these radiant plants in their garden should be replaced with something less aggressive. Even so, if you have, or are thinking of planting, ornamental jewelweed, creeping bellflower or foxglove there are some reasons to consider otherwise.

Ornamental jewelweed, impatiens glandulifera, grows about 3-5 feet high, has reddish stems, oppositely arranged toothed leaves, and showy, irregularly shaped, white to pink flowers.

On a scale of 0 to 100, its invasiveness ranking is 82. It receives its high ranking because of its high seed set and ability to crowd out native plants. One plant can produce upwards of 800 seeds. This combined with its ability to smother native seedlings with its leaf/stem litter contributes to its ability to replace native species. In addition, its showy flowers attract pollinators resulting in increased pollination of Jewelweed and decreased pollination of other beneficial native plants. If and when this plant succeeds along waterways it can alter water flow and increase erosion and flooding.

In a 2007 invasive weed road survey conducted by the U.S. Forest Service, ornamental jewelweed was found in five different locations along their 95 mile road system in Haines. Juneau has a few growing populations of Jewelweed along the road as well. This is a bad place for a prolific seed producer and aggressive invader. Jewelweed is best controlled by mowing and hand pulling before seed-set. In the pamphlet "What to Plant (and Not Plant) in Southeast Alaska" the Juneau Watershed Partnership suggests Jacob's Ladder as an alternative for local gardeners. Jacob's ladder is fragrant, self seeds, and has pretty purple flowers.

Creeping bellflower, campanula rapunculoides, grows 2-4 feet tall and has alternate, toothed leaves and purple bell shaped flowers. Creeping bellflower is of concern because it can out-compete native plants by spread and by reducing soil moisture and nutrients.

Bellflower spreads by rhizomes and seeds. Rhizomes are horizontal roots that enable plants to spread vegetatively. Seeds aid the plant in long distance dispersal. Bellflower is difficult to eradicate. Hand pulling can have some impact and selective herbicides can also be used. Although it's ease of care may be attractive, bellflower can quickly become taxing and time-consuming when it starts to take over your yard. There are a variety of less aggressive species of campanula that grow well in Southeast such as clustered bellflower, campanula glomerata.

Foxglove, digitalis purpurea, grows 2 to 5 feet tall, has soft, toothed leaves and pink to purple bell shaped flowers with mottling on the inside surface. It is one of the most beautiful invasive weeds found in Southeast gardens. Foxglove has an invasiveness ranking of 51 and spreads solely by seed. It is problematic because it colonizes disturbed soil, which could altar natural succession. It is toxic to humans and animals and so does not provide a food source and could potentially replace native food sources. Foxglove has escaped cultivation in Southeast and formed dense stands along roadsides and vacant lots. Foxglove can be controlled by hand pulling. Instead of foxglove try a variety of the equally beautiful delphiniums.

You might be surprised to find that you have one of these plants in your garden already. Or maybe you've admired them in other's gardens. While the season is coming to an end and you are looking forward to next year's garden consider replacing these species. They are listed because they have a negative ecological impact.

Let's do what we can to keep invasive species out of Alaska. You can contact the Cooperative Extension Service at 796-6241 for information about all of these invasive species, as well as learn recommendations for control and removal methods. For photos and more information on these and other non native plant species, visit akweeds.uaa.alaska.edu/.

• Marie Heidemann is the Juneau district Integrated Pest Management technician for the University of Alaska Fairbanks' Cooperative Extension Service.