Cirsium cymosum var. canovirens
Cirsium cymosum
gray-green thistle
graygreen thistle, peregrine thistle
usually 1, erect, ± gray-tomentose, sometimes villous with septate trichomes;
branches 0–10+, usually arising in distal 1/2, ascending, usually reaching a ± common height.
blades linear-oblong to oblanceolate or elliptic, 10–30 × 3–7 cm, shallowly to deeply pinnatifid with 3–8 pairs of lobes, longer than 2 cm, lobes well separated, linear to triangular-ovate, dentate to lobed proximally, main spines slender, 2–7 mm, faces green to gray, thinly to densely arachnoid-tomentose with fine, non-septate trichomes, sometimes villous with septate trichomes along veins, usually ± loose and irregularly deciduous from leaves in age;
basal often present at flowering, sessile or winged-petiolate;
principal cauline mostly in proximal 1/2, winged-petiolate or sessile, bases narrowed, auriculate, veins often prominently raised on abaxial faces;
distal sessile, auriculate-clasping or short-decurrent 1–10 mm, progressively reduced becoming bractlike, often unlobed or less deeply divided and sometimes spinier than proximal.
(0–)2–15 cm.
ovoid to hemispheric or campanulate, 2–3 × 1.5–3.5 cm, ± arachnoid-floccose, often glabrate.
creamy white to purplish, 20–31 mm, tubes 8–14 mm, throats 5.5–10 mm, lobes 6–7 mm;
style tips 4–6 mm.
in 8–10 series, subequal to strongly imbricate, green, linear to lanceolate (outer) to linear (inner), entire, abaxial faces with inconspicuous to prominent glutinous ridge;
outer and mid bodies loosely spreading to ascending or appressed, apices subappressed to ascending or spreading, flat, spines ascending to spreading, fine, 2–4 mm;
apices of inner commonly flexuous or reflexed, narrow, flat, scarious.
usually much shorter than inner; glutinous ridge prominent, well developed, appearing dark brown on dry specimens.
borne singly, terminal on main stem and branches, sometimes also in distal axils, erect, not subtended by well-developed leaves, collectively forming corymbiform or racemiform arrays.
tan to dark brown, 5–7.5 mm, apical collars not differentiated;
pappi 16–25 mm.
heads 15–25 mm diam.
= 34 (as C. canovirens).
Cirsium cymosum var. canovirens
Cirsium cymosum
Variety canovirens occurs from the dry mountains and valleys of eastern Oregon and the rain shadow slopes of the northern Sierra Nevada eastward across the northern Great Basin to Idaho, southern Montana, and western Wyoming. D. J. Keil and C. E. Turner (1993) recognized a polymorphic Cirsium canovirens that included C. subniveum (here treated as C. inamoenum). My subsequent investigations indicate that the merger of those taxa was erroneous, based in part on mis-identified specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
Past floras have treated Cirsium cymosum and C. canovirens as separate species. In my examination of these plants across their combined ranges I realized that they are connected by numerous intermediates and that I could find no characters that consistently distinguish them.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Larger heads 20–35 mm diam.; outer phyllaries elongate, often nearly as long as inner; glutinous ridge narrow, weakly developed | var. cymosum |
1. Larger heads 15–25 mm diam.; outer phyllaries usually much shorter than inner phyllaries; glutinous ridge prominent, well developed, appearing dark brown on dry specimens | var. canovirens |
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