Wednesday, September 21, 2011

Anderson's thistle along Donner Lake Rim Trail

Anderson's thistle (Cirsium andersonii), also named rose thistle, is a flowering plant in the sunflower family (Asteraceae), native to California and parts of Nevada and Oregon [1]. In the Tahoe Basin and surrounding areas in the Sierra Nevada, the thistle occasional occurs at mid elevation on dry flats and forest openings [2]. The posted plants were found in mid-September along the open stretch of Donner Lake Rim Trail (DLRT) between its junction with the Wendin Way Access Trail and Summit Lake. The tall plants occur in small groups, often in the neighborhood of some shrubs. The slender flower heads display an explosion of white, pink and rose. The green leaves should be handled with care: they contain a couple of small spines around their edges.
Note: There are about 200 Cirsium species worldwide (North America, Europe, Asia and Africa). Some of them look alike and I tried my best to match and identify the shown ones with rose thistles described in the literature and on websites—excluding other classifications. Still looking for a local thistle expert.

References and more
[1] USDA Plants Profile: Cirsium andersonii (A. Gray) Petr. - rose thistle [].
[2] Laird R. Blackwell: Tahoe WildflowersA Month-by-Month Guide to Wildflowers in the Tahoe Basin and Surrounding Areas. A Falcon Guide, Morris Book Publishing, LLC, 2007; page 84.
[3] Go on a photo tour:  Adam R. Paul | CalPhotos | Wikimedia.

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