by Sarah Walker, from the November 2004 Newsletter

Some of the pretty flowers and shrubs that we welcome into our yards and gardens are studied by plant ecologists and weed scientists—but not for aesthetic appeal or landscaping. Scientists want to understand how these exotic plants behave when they ‘escape’ from our tended gardens into surrounding native ecosystems. Native plant communities have evolved over a very long period of time and rely on associated animals, fungi and microbes to continue. A fast-growing weed upsets the balance.

The flowers in the below photo are examples of some of the many plants that flourish in gardens and also manage perfectly well—too well!—on their own, in city alleys or in the wild. What is it about a plant’s ‘lifestyle’ that makes it end up on noxious weed lists?

Japanese buckwheat — Oxeye Daisy — Scotch Broom Pretty flowers or ‘power plants’ capable of undermining native ecosystems? Photos from Field Guide to Noxious and Other Selected Weeds of British Columbia

Japanese knotweed was once considered a valuable landscaping plant. It bears showy displays of creamy white flowers in late summer. Its red, bamboo-like stems look interesting. And they grow incredibly fast. New shoots that appear each spring can reach 8–10 feet by mid-summer. Moscow has a few knotweed clumps in alleys and along streets.

Scotch broom is another perennial shrub. It produces masses of bright yellow flowers that look just like the flowers on peas. Its dark green branches look sort of broom-like, and one could make a whisk broom from them. They are hardy and spread into sunny areas.

Oxeye daisies are the subject of poems and songs. A field of daisies might seem like a blissful sight. Daisies are reliable and their familiar daisy-faces cheer the soul.

So how did the innocent daisy end up on the Wanted Posters of the plant world? The state of Washington has laws that make it illegal to sell daisy seeds, and urges gardeners to check for daisy seeds in packets sold for ‘wildflower gardens.’

Plants have life goals of their own that have little to do with our personal aesthetic! For daisies, it’s a matter of profuse seeding. A single plant can produce thousands of seeds, and each seed can germinate in a few days. New plants form dense mats of leafy rosettes close to the ground and other plants can’t get started. Then come more seeds, and so on. When daisy bouquets get discarded in the alley or out the car window, they’re ready to spread. In the wild daisies compete with native grasses in pastures or with native flowers in meadows.

Japanese knotweed grows so fast that it shades out other plants. Its roots dive deep—it’s not possible to dig up a mature Japanese knotweed without leaving bits of root down deep in the soil. It’s tough—each tiny piece of root can sprout into a new stem to start a new patch—and it can travel. It likes to grow right next to rivers. Small pieces of root get dislodged during flood season in the spring, and that’s enough material to start a new colony downstream. Japanese knotweed is bad news for Palouse waterways.

Scotch broom can grow fast, too. Its thick woody stems are hard to cut. New shoots resprout. Seed pods snap open to shoot seeds away from the parent plant. Broom was introduced from Europe 150 years ago and has become a major pest in coastal states. Recently it has taken hold in inland areas and grows in a few yards here. Wild sunny meadows outside of town are likely candidates for broom to monopolize.

Can we keep these potential invaders reined in within our own yards? It’s hard! Before you plant, check up on a plant’s habits!

For local weed lists and information on how to get rid of specific weeds, Latah Country Noxious Weed Department can help. Alan Martinson is available at (208) 883-7210. And to learn the stories of our native Palouse ecosystem check out www.palouseprairie.org.

Copyright: Copyright on articles, recipes and images are jointly held by the Moscow Food Co-op and the respective contributors, except were otherwise noted.

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