There seems to be a plant invasion in my Seattle neighborhood. I think what I’ve been seeing are larger specimens of Ailanthus altissima (Tree-of-Heaven) surrounded for many blocks by smaller seedlings of this same tree. It sprouts up through the middle of landscape plants and lawns, and right up against concrete foundations. I feel I should be warning people, but I’d like to know what the local status of this tree is, and I want to be sure I have identified it correctly. I already know it’s aggressive here, and I know it’s been designated invasive in other parts of the U.S. and the world.
You are correct that Ailanthus altissima has quite a track record for invasiveness. As you say, the U.S. Department of Agriculture’s National Invasive Species Information Center lists it. If you want to show people in your neighborhood some clear images of the tree in various stages, the Invasive Plants Atlas of the United States has good information.
If you aren’t completely certain what the plant is, you can bring samples to the Herbarium here at the Center for Urban Horticulture, or you can compare and contrast what you have observed with some close look-alikes:
Tree-of-Heaven is mentioned in a pamphlet on alternatives to invasives for Eastern Washington gardeners, but it has not yet achieved official invasive status. The Washington State Noxious Weed Control Board is considering a nomination to designate it as a Class B noxious weed (second highest priority) for the 2012 state weed list.
You could encourage your neighbors to eradicate it when possible. It spreads by seed (which can be dispersed by birds but especially by wind), and by root sprouts. It is a very fast grower, and it is important, when digging it up, to get every last bit of root, or you will soon find more of it sprouting. The California Invasive Plant Council has excellent, detailed information on its history, its growth and reproductive habits, and several methods of controlling its spread.
I have a non-native bamboo. It’s in a marshy area. It is soft light green. It dries to wood every year. And I cut it like firewood and chip it. Then suddenly it grew back and is growing to an acre size. It even flowers: soft light white vanilla flowers for the bees. Can I rototill it under and seed in native Northwest groundcovers?
It is difficult to do plant identification by description alone, but it sounds like you may have Japanese Knotweed (Polygonum cuspidatum)
It is extremely (!) hard to control this plant. Rototilling it will make hundreds of new plants because it grows from the tiniest root fragment, so do not do that!
There is a lot of good information on it on the Internet, but here are two good links:
King County, which lists it as a Class B noxious weed (control recommended but not required by law)
Washington State Noxious Weed Control Boards
I’m having difficulty removing knotweed from my garden. Can you give me advice on how to eradicate it?
I’m sorry to hear you are struggling with knotweed. Manual methods include
cutting, mowing, pulling, digging, or covering. Dig surface roots in
loose soil. Check frequently for new shoots and dig them up as soon as
you notice them. Cut stems close to the ground every two weeks throughout
the growing season. After cutting completely, you could instead decide
to cover the area of the knotweed patch and the immediate area around it
with black plastic or other impermeable material. This is a long-term
process, and it may take several years to eradicate the Polygonum. Here are some helpful links on knotweed:
Invasive Knotweeds from the King County Noxious Weed Control Program
Knotweed Biology and Control from the King County Noxious Weed Control Program
Controlling Knotweed in the Pacific Northwest (a large file!)
Japanese Knotweed from the PCA Alien Plant Working Group
Can you provide me with an extensive list of resources for checking whether a plant is invasive or a noxious weed?
Here is a list of helpful resources:
Washington State Noxious Weed List from the US Department of Agriculture
State noxious weed list and schedule of monetary penalties from the Washington State Legislature
Class A, Class B, and Class C
Washington Department of Ecology (aquatic plants)
Washington Invasive Species Coalition and their GardenWise handbook
King County Noxious Weed Lists
National Invasive Species Lists
Plant Conservation Alliance Alien Plant Invaders list
Invasives in British Columbia
The lists which are national in scope are useful too, as some plants not
yet officially listed as invasive here may still be plants to watch out
for.
There are a great many books on this subject. A recent one, co-authored
by a faculty member here, is Invasive Species in the Pacific Northwest edited by P.D. Boersma, S.H. Reichard, and A.N. Van Buren; Rebecca L. Gamboa, photo editor.
University of Washington Press, c2006.
I’m doing a science fair project on dodder plant and I’m seeking information about the plant, and a source of seeds or plants for the project.
Dodder is a parasitic plant that lives on crops, ornamentals, native plants, and weeds. Because it has limited chlorophyll, it can’t make enough food to support
itself, and so relies on the plants it colonizes for nourishment. It belongs to the genus Cuscuta, in the family Convolvulaceae (same family as morning glory). It was formerly referred to as Grammica.
Perhaps the reason that seeds and plants are not readily available is that dodder causes great damage to the plants it parasitizes. The U.S. Department of Agriculture’s plant protection and quarantine office states that “products, including foods, containing whole dodder seeds (Cuscuta spp.) are prohibited entry into the United States. APHIS regulates whole dodder seeds, both as a parasitic plant pest under Title 7 Code of Federal Regulations (CFR), Part 330 and as a Federal noxious weed under Title 7 CFR, Part 360.”
Here is additional information from University of California, Davis’s Integrated Pest Management website. Dodder is sometimes referred to as the “Vampire Plant,” as this University of Florida Extension page explains. Although your project, safe within the confines of a lab or classroom, might pose no threat, it is not legal to sell Cuscuta seeds or plants in the U.S.
A list of the best books, articles and websites on invasive plants.
Photos and descriptions for weed identification in King County, WA. Search by common name, Latin name, or thumbnail photo.
View Federal and state noxious weed lists, an invasive plant list, or an introduced plant list, each with links to more information.
The U.S. National Arboretum’s web pages on invasive plants offer, by state, resources for identification of noxious weeds, the laws and procedures pertaining to a plant’s becoming listed and many other web resources related to education about invasive plants.