|One of the more difficult invasive plants to identify are thistles. There are so many varieties and so many similarities to their native counterparts. Landowners often end up destroying native thistle while attempting to get rid of invaders. It seems herbicides and biocontrol insects can’t tell the difference, either. Native species that local wildlife relies on for food and habitat become endangered. To add to the confusion knapweed can resemble thistle, too.
Wildflowers can have interesting relatives. Thistles of members of the Asteraceae family and count Asters and Sunflowers as distant cousins. The Xerces Society’s booklet on native thistles states many native varieties “only flower once before dying” and “tend to allocate significant resources toward producing larger flowerheads” (source: https://xerces.org/publications/guidelines/native-thistles-conservation-practitioners-guide)
Instead of viewing bad invasives, we will focus on the native plants. Bees (particularly bumblebees), butterflies and moths see native thistles as sources of pollen and nectar. Many songbirds eat thistle seed. According to Wildflower Search (http://wildflowersearch.org), there over 15 native thistles in Oregon. Of those, these four belong in Harney County (any others should be considered invasives):
|Leafy, Thistle, Meadow Thistle, Elk Thistle, Drummond’s Thistle (Cirsium scariosum). Found in meadows, riparian and forests throughout Harney County and nearly every western state of the U.S. It is identifiable through the silvery hairs and spines. The stalk and flowerhead are edible.|
|Wavyleaf Thistle (Cirsium undulatum), also called plumed thistle or gray thistle. This thistle can be found in all western states, states surrounding the Great Lakes, Mexico and southern Canadian provinces. Native Americans ate the roots of this thistle and made a medicinal tea to treat eye diseases in people and livestock. This variety is becoming rare in the Midwest.|
|New Mexico thistle (Cirsium neomexicanum), also called lavender thistle, foss thistle, desert thistle, and–appropriately enough–the powderpuff thistle. This variety makes its home in the high desert and can be found in Mexico, the southwestern U.S. as well as Oregon and Idaho. In Harney County it has been seen in in the Steens Mountain.|
|Peregrine thistle, or gray green thistle (Cirsium cymosum). This thistle provides nesting materials for native bees and can be found throughout Harney County.|