May flowers you don’t want to see in your garden

All flowers are beautiful in their own way, but there are some that spell trouble in spite of their aesthetic appeal. King County noxious weed specialists shared these lovely photos of a few not-so-lovely noxious weeds seen on the job this past month.

Dalmatian toadflax on railroad tracks in Seattle, Washington. Photo by Maria Winkler.

Dalmatian toadflax is thought to have been first introduced as an ornamental, but is better known now for its invasion in rocky, dry soils such as along railroad tracks. This stunning patch of toadflax escaped notice last year because there had been a train parked right over it. One of the many hazards of trying to root out noxious weeds!

Garlic mustard flowering and beginning to form seeds. Photo by Karen Peterson.

Garlic mustard is almost all in seed by late May, but there are always a few late-flowering plants such as these. One of the trickiest things about this species is its ability to avoid detection and continue to form seeds in spite of all efforts to find all the plants.  And a single plant makes enough seeds to take over a huge area.

Orange hawkweed in flower. Photo by Mary Fee.
Orange hawkweed flowers seen from above. Photo by Mary Fee.

Orange hawkweed has such brilliant, flame-colored flowers that people sometimes collect them from our mountain roads thinking they must be native wild-flowers, instead of the European transplants they are.  Unfortunately, once introduced, orange hawkweed spreads out by stolons to crowd out other plants, including the our local Pacific northwest wildflowers.

Tansy ragwort flowering behind a fence.  Photo by Mary Fee.

It’s surprising and more than a little discouraging to see tansy ragwort in flower already in May, since it means a long, difficult summer of trying to stop it before it goes to seed. This plant is the bane of livestock owners here in the Pacific Northwest as well as back in its native lands in western Europe. Toxic to many animals and a prolific seeder, this weed has many reasons to dislike it.  A single plant can produce enough long-lived seeds to ensure its presence in a pasture for the next 10 to 15 years.

Yellow archangel flower closeup in April. Photo by Roy Brunskill.

Yellow archangel is really more of an April flower, but it is always around due to its evergreen leaves.  The silvery-green foliage is the plant’s main attraction in hanging baskets and flower beds, but don’t be fooled.  Yellow archangel is one of the most invasive plants we have and also very difficult to get rid of once it’s escaped into the woods.

Yellow flag iris in Soos Creek.  Photo by Erin Haley.

Yellow flag iris is a European species, but it’s so well-established in wet areas of the Pacific Northwest that you would think it’s native. I’ll admit that it can look quite lovely. However, the risk it poses to the native vegetation and the habitat value of the stream or wetland ruins the view for me.

Scotch broom flowers against the sky.  Photo by Karen Peterson.

Scotch broom has been in full flower for some time now and is already starting to form seed pods. This plant is such a familiar sight, it’s hard to imagine a time when it didn’t line our hillsides and roads. Fortunately, a little elbow grease and persistence can overcome this weed, especially when combined with planting trees or other shade-producing vegetation.

Creeping buttercup in flower. Photo by Steve Burke.

Although not technically a noxious weed in Washington, creeping buttercup has earned its bad reputation with everyone from home gardeners to horse-lovers to hay growers. This plant is equally at home in a lawn or garden as it is in a natural wetland or creek edge. It is hard to believe that the species was introduced from Europe given how entrenched it is now in our region. More than once I’ve come across creeping buttercup high up on a mountain trail far from most other non-native plants. And of course there’s that annoying patch in my lawn that I walk by every day.