Purple Loosestrife, an invasive species, in a garden
Yesterday, in Time to Get Tough, Emily DeBolt introduced the topic of invasive plants and legislation in the Northeast to control their sale. Today I’d like to take the conversation to the opposite coast where I live in Washington State.
Washington’s Noxious Weed Board issues an annual list of noxious weeds. The list is divided into three classes (quoting from the Noxious Weed Control board website):
- Class A: Non-native species that are limited in distribution in Washington. State law requires that these weeds be eradicated. Click here to see Washington State’s Class A noxious weeds.
- Class B: Non-native species that are either absent from or limited in distribution in some portions of the state but very abundant in other areas. The goals are to contain the plants where they are already widespread and prevent their spread into new areas. Click here to see Washington State’s Class B noxious weeds.
- Class C: Non-native plants that are already widespread in Washington State. Counties can choose to enforce control, or they can educate residents about controlling these noxious weeds. Click here to see Washington State’s Class C noxious weeds.
The state prohibits the sale or distribution of all plants on the Class A list, as well as some on the Class B list.
Oregon has a similar noxious weed list, administered by the Department of Agriculture. California has Encycloweedia to spread the word about invasives in the golden state. Look for the list for your state with an online search of “state name noxious weed list.”
The Unknowing Gardener
Gardeners can be unwitting villains in the spread of invasive plants. We think we’ll be able to keep non-native plants under control, that they won’t survive our winter, or that it just doesn’t matter whether there are consequences to the plants we love.
White Butterfly Bush with Tiger Swallowtail
A commonly grown garden plant, butterfly bush (Buddleja davidii) is on the Class B list, but sale is not prohibited at this time in Washington. It’s particularly invasive along streams, sometimes reaching considerable distances upstream away from homes and gardens. It crowds out native species that have much greater wildlife value, even though butterflies do nectar on it. While there’s no current mandate to cut down and destroy every butterfly bush in Washington gardens, it’s one that should be removed over time. Since it thrives in disturbed soil, digging it up may not get all the pieces, leading to even more vigorous stands. Up in British Columbia I see it in freeway medians and it’s popped up through the asphalt next door to our home.
Purple Loosestrife
Purple loosestrife (Lythrum salicaria), is another plant I’ve seen in gardens across the country. It’s on the Washington Class B list and is expressly prohibited from sale or transport (WAC 16-752-400 – 415). This pretty purple flower is invasive in wetlands, dominating a site. It provides poor cover for waterfowl.
Old Man’s Beard (Traveler’s Joy)
We’re not plagued by kudzu in Washington (and yes, it’s on the list), but we do have a widespread and pretty climbing vine that is invasive. Old man’s beard (Clematis vitalba) is sometimes known as traveler’s joy. Its feathery seed heads linger through the winter, glowing on the rare sunny days this time of year. It has small white flowers in mid-summer. The similar-looking native western white clematis (Clematis ligusticifolia) is widespread on the east side of the Cascades.
The noxious weed list has its origins in agriculture, where weeds invading pastures can degrade the value of forage for livestock or are toxic to cattle. Driving around the northwest, it’s not unusual to see a large sign at each county boundary reminding people that it’s their responsibility to control noxious weeds. We’re also concerned about the introduction of aquatic weeds that can quickly choke ponds, lakes, and wetlands. Locally, Bellingham instituted boat inspection stations at the main boat launch on Lake Whatcom last year to look for invasive species being transported into our drinking water source (yes, boating is allowed on the lake where we get our water). The inspectors found both invasive plants and shellfish.
Yellow Flag Iris in garden pond
The notion that some invasives are too well established to be eradicated is supported by Class C weeds on our state list. These include plants like English ivy (Hedera helix), Himalayan blackberry (Rubus armeniacus), oxeye daisy (Leucanthemum vulgare), and yellow flag iris (Iris pseudacorus). Control of these is on a county-by-county basis.
One thing you’ll note when looking at noxious weed lists is that a plant which is well-behaved in one climate or environment is a nasty pest somewhere else in the country. Emily wrote about Norway maple and burning bush being problems in her part of the Northeast, but they’re not serious problems in Washington. There are other and better choices to plant but we’ll expend our energy on more problematic species.
Choosing Alternatives
There are two publications called Garden Wise that help gardeners choose alternatives to invasive species and cultivars. Not all the alternatives are native, but the goal is to educate and reduce the number of invasive species in the landscape more than to push people to garden with natives only. There are separate guides for western and eastern Washington.
While it’s not organized by invasive/alternative, the Washington Native Plant Society website has extensive resources for choosing native plants appropriate to a wide variety of habitats within the state. Look for the Native Plants for Western Washington Gardens and Restoration Sites page on the WNPS website.
What are the problem plants in your area? Are they on your state’s official noxious weed list? Should you and your friends lobby the appropriate agency to add one or more plants to the list?
Addendum February 9, 2013:
The South Sound Chapter of the Washington Native Plant Society’s monthly program in Olympia on Monday, February 11 will feature a program on the state’s noxious weeds. If you’re in the area, join the conversation.
Monday, February 11, 2013 7pm (Olympia) – Wendy DesCamp
Washington State Noxious Weeds: Laws, the Weed Board and Noxious Weed Species
This presentation will provide an overview of the noxious weed laws in Washington and the Washington State Noxious Weed Control Board membership and roles. Our state’s noxious weed list is large and diverse, and we’ll talk about how and why these plants are listed. We’ll review our newest noxious weed list additions and discuss some lesser known noxious weed species that can grow in this area.Wendy DesCamp is the Education Specialist for the Washington State Noxious Weed Control Board. She received her B.S. in Biology and M.S. degree in Forest Resources from the University of Washington and researched yellow archangel (Lamiastrum galeobdolon) for her thesis. Before the Weed Board, Wendy’s past work included being the Collections Manager for the Otis Douglas Hyde Herbarium at the University of Washington Botanic Gardens and working for the Pacific Northwest Invasive Plant Council.
Meeting Location:
Washington State Capitol Museum Coach House
211 West 21st Avenue
Olympia, WA 98501
360.753.2580Directions to the Washington State Capital Museum: From Interstate 5 in Olympia, take Exit 105, following the “State Capital/City Center” route. Go through a tunnel, (get in the left hand lane) and turn left on Capital Way. Follow the brown and white “State Capital Museum” signs to 21st Avenue. Turn right on 21st Avenue and proceed two blocks. The museum is on the left in a stucco mansion. We meet in the carriage house in back of the mansion.
© 2013, Mark Turner. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us
About Mark Turner
Thanks Mark! I think a lot of gardeners just don’t realize that species in their own gardens may be invasive. I just recently found out about butterfly bush and have removed the one in my garden. Guess we just need to keep getting the word out.
Christy Peterson recently posted..Creature of the Week—Groundhog (of course!)
FYI, my understanding is that all states have noxious weed laws, and there are also federal noxious weed laws. However, most of these lists are maintained by state Departments of Agriculture, and thus there is a heavy-to-exclusive focus on AGRICULTURAL weeds. Only rarely to they include plants that threaten natural environments. Washington seems to be unique in that it has a handful of non-agricultural weeds, but unfortunately I believe that is the exception, rather than the rule.
Nonetheless, Washington’s example shows that adding invasive plants to state noxious weed lists is a potential strategy for regulation, as opposed to creating entirely new sets of regulations, as is being done in several eastern states.
Sometimes there are also alternative options for gardeners. For instance, there are sterile butterfly bush varieties that can be grown anywhere (Flutterby series). I’m not sure if this would benefit the ecosystem, but it’s a compromise that let’s the gardener enjoy a beautiful plant that won’t do serious damage to the environment.
Tony recently posted..Starting Milkweed Seeds Indoors Part III
Tony, those sterile cultivars are a possible compromise in the short term. But even a sterile butterfly bush doesn’t provide the same diverse food and habitat features that native species do. Reducing the spread of these invasive plants is a good thing, and gardeners have a long history of growing exotic species. So maybe the small step of non-reproductive cultivars is an OK thing, at least in the short term.
Mark Turner recently posted..Frost Flowers
I’m in a southwest suburb of Chicago. Japanese Barberry & Burning Bush are very popular & are planted everywhere. I don’t think people realize how invasive they are. The thought about invasive species never enters their mind. I like this pretty bush so I’m going to plant it. Others think it’s ok to plant, since it’s being sold by local nurseries.
I’ve encouraged non gardeners & beginners to plant a few native flowers this year. A friend who has hummingbirds visit is happy to have me plant natives, she gets it. I’ve explained the importance of planting native & supporting the environment, to those who have asked me to help with getting a garden established. People don’t seem to care about planting inasive, planting host/nectar plants, nor do they connect their gardens to the bigger environmental picture. It’s an uphill extremely frustrating battle. One absoulute must I got is, no worms, & no insects in the garden. There are some things that I, as a butterfly gardener, can’t accomadate. The garden is life, & those who understand that are truely blessed.
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