Cirsium ciliolatum (Henderson) J. T. Howell

Cirsium ciliolatum is restricted to a few sites in and around the Klamath Range of Jackson County, Oregon, and Siskiyou County, California. It is listed by the state of California as endangered. It is closely related to C. undulatum and perhaps should be treated as a variety of that species. Pending a comprehensive study of the variation within C. undulatum, I have maintained C. ciliolatum as a distinct species.

Perennials 60–200 cm, arachnoid, tomentose; runner roots producing adventitious buds. Stems 1–several, erect, thinly arachnoid to densely white-tomentose; branches 0–few, ascending. Leaves: blades oblong-elliptic, 10–30 × 3–12 cm, margins finely spiny-toothed and otherwise undivided to coarsely dentate, shallowly lobed, or deeply laciniate-pinnatifid, lobes broadly triangular to linear-lanceolate, main spines 1–6 mm, abaxial white-tomentose, adaxial faces ± green, thinly to densely arachnoid-tomentose; basal often present at flowering, winged petiolate; principal cauline well distributed, proximally winged-petiolate, distally sessile, gradually reduced, bases auriculate. clasping or short-decurrent as spiny wings; distal cauline few, reduced to linear bracts. Heads borne singly and terminal on main stem and branches, or few in corymbiform arrays. Peduncles 0–15 cm. Involucres ovoid to hemispheric, 1.5–2.3 × 1.5–3 cm, thinly arachnoid, ± glabrate. Phyllaries in 5–7 series, strongly imbricate, greenish with subapical darker central zone, lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge; outer and middle bodies appressed, entire, apices entire or finely serrulate, spines ascending, slender, 1–3 mm; apices of inner spreading to erect, narrow, ± flattened, finely serrulate, ± scabrous. Corollas dull white to lavender, 15–25 mm, tubes 7–11 mm, throats 5–7 mm, lobes 5–7 mm; style tips 5–7 mm. Cypselae brown, 3.5–7 mm, apical collars tan, 0.1–0.2 mm; pappi white or tawny, 15–20 mm.

Cirsium undulatum (Nuttall) Sprengel var. ciliolatum L. F. Henderson, Bull. Torrey Bot. Club 27: 348. 1900 (as Circium); C. howellii Petrak

Cirsium ciliolatum is a species of thistle known by the common name Ashland thistle. It is endemic to the Klamath Mountains, where it is known from only a few occurrences in Jackson and Josephine Counties in Oregon, as well as neighboring Humboldt and Siskiyou Counties in California. It is related to Cirsium undulatum and may be more accurately described as a variety of that species.

Cirsium ciliolatum is a perennial herb growing from a rootstock branching with runner roots to a maximum height near 200 cm (79 in). It is cobwebby with fibers. The gray-green woolly leaves are smooth along the edges to deeply lobed, sometimes spiny and cobwebby, and up to 25 centimeters at the longest. The inflorescence is a cluster of several flower heads each about 2 centimeters long and up to 5 wide. The head is lined with sticky, spiny phyllaries and packed with white to lavender flowers. The fruit is an achene with a thick body a few millimeters long and a pappus about 1.5 centimeters in length.

Cirsium ciliolatum là một loài thực vật có hoa trong họ Cúc. Loài này được (L.F.Hend.) J.T.Howell mô tả khoa học đầu tiên năm 1959.