[Thistles: The Genus Cirsium in the Columbia River Gorge of Oregon and Washington]

Wavy-leaf Thistle

Cirsium undulatum

Synonym: Cirsium undulatum var. undulatum

Involucral bracts of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

The photo above shows a close-up sideview of the flower head of wavy-leaf thistle as seen along the Dalles Mt. Road above 2000'........July 7, 2006. Note the long spines at the tip of each involucral bract as well as the grayish longitudinal markings along the middle of each bract which make the flower heads of this species attractive.

Upper stem of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)The photo at right shows a close-up sideview of the flower head and upper stem of wavy-leaf thistle as seen along the Dalles Mt. Road above 2000'........July 7, 2006.
Characteristics:

Wavy-leaf thistle is a stout, single-stemmed short-lived perennial. The stem may be branched above, and stems range from 30-120 cm tall. All surfaces of the stem and leaves are persistently white-woolly haired, although the upper leaf surfaces may be less covered, and occasionally may be glabrous. The stems, leaves and flower heads are covered with sharp spines.

The leaves are coarsely toothed to pinnatifid. The teeth or lobes are usually greater than 7 mm wide. The heads are generally several to numerous and found at the ends of the branches. The involucre ranges from 2.4-4 cm high. The outer bracts are spiny tipped as seen in the photos. The flowers are pinkish-purple.


Habitat:

Wavy-leaf thistle is found in dry, open, well-drained habitats, and frequently in sand or gravel in the lowlands and foothills.


Range:

Wavy-leaf thistle may be found east of the Cascade Mountains from southern British Columbia south through central Washington to northern Oregon, then east across northern Idaho to the northern Great Plains. It may rarely be found as far south as southeastern Arizona.

In the Columbia River Gorge, it is found between elevations of 200'-2700' from near The Dalles and east to near Haystack Butte.


Flower head of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

The photo at left shows a close-up view down onto the disk of wavy-leaf thistle as seen along the Dalles Mt. Road above 2000'.........July 7, 2006. The photo at right shows a late-blooming wavy-leaf thistle as seen along the old rail trail on the east bank of the Deschutes River, Deschutes River State Recreation Area.........November 12, 2017.

Basal leaves of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Basal leaves of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Close-up photos of the cluster of basal leaves of wavy-leaf thistle. The photo at left was taken along Washington Highway 14 at Milepost 91 above Avery, WA.........October 7, 2006 while that at right was taken along Washington Highway 14 at milepost 115.5........May 11, 2009.

Flower head of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Upper stem and inflorescence of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Involucral bracts of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Close-up views of wavy-leaf thistle as seen along Washington Highway 14 several miles west of Roosevelt, WA..........June 16, 2009.

Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Wavy-leaf thistle still blooming in the Columbia Hills State Park above the Crawford Oaks Trailhead.........October 12, 2013.

Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Flowerhead of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Wavy-leaf thistle still blooming (left) along the old railroad bed above the east bankof the Deschutes River about 2 miles south of its mouth, Columbia River Gorge..........November 1, 2014. Wavy-leaf thistle still blooming (right) along the old railroad bed above the east bankof the Deschutes River about 2 miles south of its mouth, Columbia River Gorge..........October 6, 2016.

Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

An early season rosette of basal leaves of wavy-leaf thistle (left) as seen on rocky grassland slopes above and to the northeast of the Crawford Oaks trailhead, Columbia Hills State Park..........February 18, 2015. The photo at right shows a basal leaf rosette of wavy-leaf thistle as seen on the southeast side of Horsethief Butte, Columbia Hills State Park........January 18, 2016.

Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Basal leaf rosette of wavyleaf thistle as seen along trails on the lower Deschutes River......January 4, 2019.

Basal leaves of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum) - Basal leaves of Wavy-leaf Thistle: Cirsium undulatum Synonym: Cirsium undulatum var. undulatum)

Early season leaf rosettes of wavy-leaf thistle as seen above the Crawford Oaks trailhead at Columbia Hills State Park..........January 15, 2016

Paul Slichter