I love our parks. The open spaces in and around Boulder are part of what makes it such a special place. We live in a beautiful bubble; open forested foothills to our west, gradual open slopes to our north, and thriving farms and grasslands to our south and east.

Many Boulderites know that the open space doesn’t just benefit the citizenry, but a huge array of life. In fact, Boulder County has the highest number of unique species of birds, plants, and mammals in Colorado.

Unfortunately, this is all threatened by invasive species. One such weed is purple loosestrife, both pretty and evil.

About the Plant
Purple loosestrife, Lythrum salicaria, is a 4-10 ft tall perennial with spikes full of pink flowers. It has lance shaped leaves and a square stem and was imported from Eurasia as a hardy garden plant. It exists in most of the United States and Canada and in Colorado it is a “List A” noxious weed. “List A” means that it is mandated for eradication, so landowners (public and private alike) must get rid of it.

Before I even try to persuade you of it’s evilness, I will first admit to it’s beauty. It is such a bright pink purplish loveliness! But we don’t need it around. And here’s why.

  • Displaces Habitat: So plants are the base of the food chain and every plant is used in a variety of ways by a multitude of creatures in its native habitat. The creatures that use purple loosestrife simply don’t exist here, so it goes unused, beneficial to no one. Plants compete with each other for resources, even space, and purple loosestrife displaces native plants and therefore habitat of native animals.  Native animals loose their nesting sites, food sources, etc. Obviously this is not good for wildlife, but the effects could be far more reaching.
  • Changes ecosystems: Purple loosestrife requires a wetter environment and loves to be along waterways and in wetlands. Wetlands are some of our most valuable ecosystems- they literally filter the environment, like a giant sponge. Purple loosestrife can spread over wetlands and crowd out the valuable plants and therefore change that ecosystem.
  • Spreads Rapidly: Each plant can produce up to 3,000,000 seeds annually that are each viable for about 20 years. Purple loosestrife also spreads vegetatively form it’s extensive root system. It easily becomes a monoculture and a huge problem.
  • Restricts Waterways: Do you enjoy the occassional canoe trip or perhaps simply eating local produce? Purple loosestrife restricts and clogs waterways which prohibits recreation and has the potential to block irrigation ditches farmers use in Colorado to irrigate crops.

So what can you do? 
First, make sure you don’t have any purple loosestrife on your property. Next, educate yourself or others because communication is key to actually getting rid of this evil plant.

More Info
This plant is a huge problem across the country so there is a ton of information out there. City of Boulder has their own info page which landowners around Boulder may find most helpful.  The Colorado Department of Agriculture is also a good resource.

There are many other flowers that look quite similar and are controllable- heck, even native and beneficial for more than just your eyes. (Anyways purple loosestrife is illegal to sell in Colorado).

1.  2. 

3.  4. 


1. Spiked Speedwell- Veronica spp.
2. Dotted Gay Feather – Liatris punctata
3. Larkspur/ Delphinium
4. Fireweed- Epilobium spp *(I recommend this one!)
5. Violet Sage- Salvia superba