The USU Weed Web (See Letter E) lists Grindelia squarrosa as an invasive weed, but does not include Euphorbia myrsinites. I am simply bowled over by this.
Curlycup gumweed (Grindelia squarrosa) is a native plant that grows well in the dry soils of the mountain west. The plant is used in some medicines, but it really is not good for the kidney. Livestock don't eat it. Since lifestock avoid the plant, the plant displaces desirable feed in overgrazed areas.
Yes, the BLM and other landowners are wise to take measures to cut back curlycup gumweed, but it doesn't belong on a list of invasive weeds of the Mountain West. As the plant is native and is not noxious like poison ivy, there should not be a concerted government action to irradicate it.
Donkey Spurge, on the other hand, is noxious and invasive in every way. The plant was imported from Turkey. The white sap of the plant is both harmful to humans and livestock. It is flourishing in the Wasatch, and appears to be displacing native species. It also appears to be extremely harmful to native animals. (I assume that native animals are adapted to curlycup gumweed.)
The USU Weed Web includes the statement:
Of the 6,741 plant species that are recognized as weeds in the world, 2,063 are currently present in the United States.
This implies that USU is determining that a plant is invasive based on a global list. This is bad science. It seems to me that a plant is not invasive in its native ecosystem. It still might be a weed, but not invasive. Yes, there are ecosystems where gumweed should be considered an invasive weed ... just not in Utah. Conversely, I believe that we should actively work to irradicate Donkey Spurge in Utah. Turkey, the native habitat of donkey spurge, should not irradicate the plant.
Curly cup gumweed is a really cool plant. I think it is an ideal plant for native rock gardens as it blooms later in the year. I actually gathered seeds and planted them last year. Damn, I am now in violation of Utah's invasive species law for planting a native plant.