Cirsium remotifolium
Cirsium scariosum
few-leaf thistle, mountain thistle, Pacific fringe thistle, remote-leaf thistle, weak thistle
chardon écailleux, dinnerplate thistle, elk thistle, meadow thistle
usually 1, erect, finely arachnoid-tomentose, sometimes villous with septate trichomes below nodes;
branches 0–10+, slender, usually arising in distal 1/2, ascending.
absent, or with crowded branches from near base, or simple and erect, often fleshy and thickened, glabrous to thinly gray- tomentose, often villous with septate trichomes.
blades linear-oblong to oblanceolate or elliptic, 7–30 × 1–15 cm, unlobed and spinulose to dentate or shallowly to deeply pinnatifid, lobes well separated, linear to triangular-ovate, dentate to deeply lobed, main spines 2–5 mm, slender, abaxial faces green to gray, thinly to densely arachnoid-tomentose, sometimes glabrate, sometimes villous with septate trichomes along veins, adaxial green, glabrous;
basal sometimes present at flowering, sessile or winged-petiolate;
principal cauline mostly in proximal 1/2, winged-petiolate or sessile, bases narrowed, sometimes auriculate;
distal well separated, progressively reduced, becoming bractlike, often unlobed or less deeply divided than the proximal, sometimes spinier than proximal, bases often distally expanded and auriculate-clasping.
blades linear to elliptic, 5–20 × 3–7 cm, plane to strongly undulate, unlobed or shallowly to deeply pinnatifid, lobes linear-lanceolate to broadly triangular, closely spaced, spreading, spinose-dentate or lobed, main spines slender to stout, 2–15+ mm, abaxial faces glabrous or thinly to densely tomentose, ± villous with septate trichomes along the veins, glabrate or trichomes persistent, adaxial thinly arachnoid tomentose and soon glabrescent;
basal often present at flowering, sessile or winged-petiolate;
cauline many in caulescent forms, reduced distally or not, winged-petiolate or distal sessile;
distal often well developed, similar to proximal, sometimes much narrower and bractlike.
(0–)2–15 cm.
0–10 cm, leafy-bracted.
ovoid to hemispheric or campanulate, 1.5–2.5 × 1.5–3.5 cm, glabrous to arachnoid-floccose.
ovoid to hemispheric, 2–4 × 1.5–6 cm, loosely arachnoid on phyllary margins or glabrate.
creamy white to purple, 18–28 mm, tubes 7–12 mm, throats 5–12 mm, lobes 3.5–7 mm, style tips 4–6 mm.
white or pale lavender to purple, 20–40 mm, tubes 7–24 mm, throats 4–12 mm (noticeably larger than tubes), lobes 4–10 mm;
style tips 3.5–8 mm.
in 6–8 series, subequal to strongly imbricate, green, linear to obovate (outer) to linear (inner), abaxial faces with inconspicuous glutinous ridge;
outer and middle bases appressed, margins entire to spinulose-dentate or broad, scarious, lacerate-dentate, spines absent or ascending to spreading, 1–2 mm;
apices of inner sometimes flexuous or reflexed, narrow, flat, entire or expanded, scarious, and lacerate-dentate.
in 5–10 series, imbricate, ovate or lanceolate (outer) to linear or linear-lanceolate (inner), margins (outer) entire or scarious-fringed, abaxial faces without glutinous ridge;
outer and mid appressed, spines erect to spreading 0.5–13 mm;
apices of mid and inner narrowed and scabro-denticulate or with expanded, erose-dentate tips, spineless or tipped with flattened spines.
few–many, borne singly or in openly branched in corymbiform, racemiform, or paniculiform arrays on main stem and branches, sometimes also in distal axils, not closely subtended by clustered leaf bracts.
1–many, erect, borne singly or often densely crowded in spiciform, racemiform, or subcapitate arrays, especially in acaulescent or short-caulescent plants, often closely subtended by distalmost leaves.
tan to dark brown, 4.5–5.5 mm, apical collars differentiated or not;
pappi 13–23 mm.
light to dark brown, 4–6.5 mm, apical collars usually colored like body;
pappi 17–35 mm, white to tan.
= 32.
= 34, 36.
Cirsium remotifolium
Cirsium scariosum
Varieties 3 (3 in the flora).
Cirsium remotifolium occurs from the Coast Ranges and valleys of the Pacific Northwest to the western slopes of the Cascade and Klamath ranges, south in the California North Coast Ranges to the San Francisco Bay region. It is closely related to the C. clavatum complex of the Rocky Mountains region. Both have a similar growth habit and some forms variably express the character of broadly scarious, lacerate-toothed phyllary margins. Gray, in naming Cnicus carlinoides var. americanus, included as syntypes both California and Colorado specimens. F. Petrak (1917) treated both the West Coast plants and those of the Rocky Mountains as Cirsium subsect. Americana, recognizing C. remotifolium with several infraspecific taxa plus two other species, C. callilepis and C. amblylepis from the West Coast, and four additional species from the Rocky Mountains. A. Cronquist (1955) rejected Petrak’s subspecies, treating C. remotifolium in a restricted sense, limited to plants of Washington and Oregon without dilated phyllary tips, and circumscribed C. centaureae broadly to include the Rocky Mountains and West Coast plants with dilated phyllary tips. Because of the frequent presence of dilated phyllary tips in C. remotifolium in the restricted sense, Cronquist acknowledged the likelihood of past introgression with C. centaureae in the broad sense.
J. T. Howell (1960b) recognized three species: Cirsium remotifolium, C. acanthodontum, and C. callilepis, the latter with four varieties collectively corresponding to the West Coast representatives of C. centaureae (in the sense of Cronquist). Because of the great similarity of the various West Coast plants and their intergradation, I see no value in recognizing two or more species.
The West Coast and Rocky Mountains plants are clearly related, but are separated by the Great Basin region and there is little chance of current genetic interchange. As is often the case with American Cirsium, genetic enrichment from past hybridization with other nearby species within their respective areas has likely been fertile ground for evolutionary diversification. Different species have contributed genes in the Pacific states and in the Rockies. I have chosen to recognize two geographically-based species complexes, each with intergrading races here treated as varieties. I treat the West Coast plants as C. remotifolium and the Rocky Mountains plants as C. clavatum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 8 (8 in the flora).
Cirsium scariosum is a widely distributed complex of intergrading races distributed from southwestern Canada to northwestern Mexico. These plants range from acaulescent rosettes with a tight cluster of sessile heads to tall, erect, unbranched plants, or moundlike, more or less openly branched herbs. Acaulescent and caulescent plants sometimes occur in the same population.
Members of this complex have been variously treated in the past. F. Petrak (1917) recognized ten species plus several subspecies for the taxa I am treating here as C. scariosum (in the broad sense). In floras, the names C. drummondii and C. foliosum have been widely misapplied to these plants (R. J. Moore and C. Frankton 1964). The latter two species, while clearly related to C. scariosum, have a range restricted mostly to Canada. Moore and Frankton (1967) attempted to bring order to the complex and recognized four species for plants that I include here in C. scariosum: C. acaulescens, C. congdonii, C. coloradense, and C. scariosum in the restricted sense. Moore and Frankton substituted the prior name C. tioganum for C. acaulescens. Unfortunately they did not extend their study widely enough and did not include some members of the complex in their investigations. S. L. Welsh (1982) proposed C. scariosum var. thorneae from Utah and lumped the various species recognized by Moore and Frankton within a highly polymorphic var. scariosum. After consulting with A. Cronquist and studying his manuscript treatment of Cirsium for the Intermountain Flora, D. J. Keil and C. E. Turner (1993) also accepted a broadly construed C. scariosum. Cronquist (1994) treated C. scariosum as an extremely variable species that included the four species recognized by Moore and Frankton plus the variety proposed by Welsh. Cronquist chose to not recognize infraspecific taxa.
In the present treatment I have examined these plants from a biogeographic perspective with the goal of discerning regional patterns of variation. The large number of specimens available has allowed me to examine distributional patterns in relation to the topography and biogeographic history of the regions where this species occurs. My field studies also have provided me with observations that help to explain some of the anomalous specimens represented in herbaria. Although the variation within and between populations is sometimes amazing, more-or-less differentiated geographic races can be discerned. Because of the extraordinary and overlapping patterns of variation across the range of Cirsium scariosum, the following key to varieties should be regarded as at best an approximation.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Phyllary margins ciliate with tiny spreading to recurved spines | var. rivulare |
1. Phyllary margins unappendaged or dilated, scarious, and ± lacerate-toothed | → 2 |
2. Phyllaries narrowly oblong or linear, often ± subequal, all or most without scarious-dilated margins | var. remotifolium |
2. Phyllaries oblong to obovate, often strongly graduated, most or all with dilated, scarious, erose to lacerate-dentate margins | var. odontolepis |
1. Plants acaulescent (occasional short-caulescent individuals sometimes present in a population) | → 2 |
1. Plants caulescent (occasional acaulescent individuals sometimes present in a population) | → 4 |
2. Corollas pink to purple; Sierra Nevada of w Nevada and e California to San Bernardino Mountains of s California | var. congdonii |
2. Corollas white to faintly pink-or lilac-tinged; widespread | → 3 |
3. Abaxial leaf faces usually gray-tomentose; widespread, Colorado to s Oregon, n California | var. americanum |
3. Abaxial leaf faces usually green, glabrous or glabrate; s. California | var. citrinum |
4. Larger leaf spines 1–3 cm | Cirsium scariosum var. thorneae |
4. Larger leaf spines usually shorter | → 5 |
5. Corollas purple | → 6 |
5. Corollas white to faintly pink- or lilac-tinged | → 7 |
6. Corolla lobes 5.5–8 mm; sw. Idaho, n Nevada, se Oregon | var. toiyabense |
6. Corolla lobes 3.5–6 mm; e Oregon to sw Montana | var. scariosum |
7. Stems usually proximally branched, plants often forming low, rounded mound; heads usually borne on short to ± elongate lateral branches; corollas 26–36 mm | → 8 |
7. Stems usually erect, proximally unbranched; heads usually sessile or short-pedunculate in subcapitate to spiciform or racemiform arrays, usually closely subtended by numerous distal leaves; corollas 20–29 mm | → 9 |
8. Apices of inner phyllaries acuminate and entire or rarely toothed; s California | var. citrinum |
8. Apices of inner phyllaries usually expanded as a scarious, erose-toothed appendage; ne California, se Oregon | var. robustum |
9. Heads usually ± tightly clustered at stem tips, closely subtended and often overtopped by crowded distal leaves; distal leaves ± thin, usually fringed with numerous weak spines, often ± unpigmented proximally or tinged pink to purplish | var. scariosum |
9. Heads usually in ± leafy, racemiform arrays, usually subtended by ± reduced, bractlike distal leaves; distal leaves firm, strongly spiny, usually green throughout | var. coloradense |
- Local floras:
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
- Local floras:
BC, CA, OR, WA - Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog.
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
