My Portland, Oregon sidewalk median strip is full of invasive species Lesser Calendine.
The species is so prolific it’s one of 7 plants not allowed in Portland City compost (we have a city wide compost pick up program).
It’s destroyed entire ecosystems in the NE United States where it was first introduced from Europe.
The plant grows early in the season and spreads via its roots and seeds that form after it flowers. What’s particularly bad about this plant is that its roots prevent other plants from growing. So it grows and blooms from February – April, but for the rest of the year, it leaves a dead zone.
We’ve been cutting it back to prevent it from going to seed, slowly pulling it up and putting it in the trash. We’ve also had some success smothering it.
If you see it in a park, or your yard, please pull up what you can and put it in the trash.
You don’t have to take my word for it. The City of Portland calls this plant “the death of dirt” (Source).
Other Invasive Species In Portland That Can’t Be Composted
I contacted the city on this, and here are the invasive plants that are so resilient and destructive that they shouldn’t be composted in city compost, or your own.
- Italian Arum
- Spurge Laurel
- Yellow archangel
- Lesser celandine
- Pokeweed
- Garlic mustard
Contact the Portland parks/city if you see any of these growing in large areas of public land.
More photos and info from the city:
https://www.oregonmetro.gov/news/getting-rid-invasive-weeds-your-backyard
I’m so glad I found this article. I’m in West Linn, and suddenly discovered a small patch of Lesser Calendine growing on the side of my house today.
The only reason it caught my attention is because a friend found a large patch of it growing on his property in Salem a couple years ago, and when we were surprised at the urgent online warnings about it when we looked it up.
It happens to be growing in some wood chips that I picked up on Craigslist. But I haven’t seen them (or any other unwanted weed) growing anywhere else where I spread the wood chips, so it’s possible a seed blew in.
Scary stuff!