Cirsium joannae S. L. Welsh, N. D. Atwood & L. C. Higgins

Cirsium joannae is endemic to Zion National Park in southwestern Utah. It apears to be most closely related to C. rydbergii, which occurs in similar habitats in southeastern Utah and northeastern Arizona.

Perennials, 100–150 cm; caudices taprooted. Stems 1, fleshy, erect, openly branched in distal ¹/2, glabrous; branches on distal stems several, ascending. Leaves: blades oblong, 10–50 × 6–12 cm, margins usually not strongly undulate, coarsely dentate or shallowly to deeply pinnatifid with 10–15 pairs of lobes, teeth or lobes ± closely spaced, not much overlapping, narrowly to broadly triangular, spiny-dentate or larger shallowly 3–5-lobed, main spines 2–12 mm, abaxial faces glabrous, adaxial glabrous; basal present at flowering, petiolate or spiny winged-petiolate; principal cauline many, well distributed, proximally ± winged-petiolate, distally sessile, gradually reduced, less divided, bases auriculate-claping and/or decurrent as spiny wings to 2 cm; distal much reduced. Heads several–many, erect or nodding, usually sessile or short-pedunculate, crowded in subcaptitate or short, spiciform clusters at branch tips, collectively forming open, paniculiform arrays. Peduncles 0–2 cm Involucres green, ovoid to campanulate (not including spreading phyllary apices), 2.5–4 × 2.5–3.5 cm, appearing glabrous. Phyllaries in 5–7 series, unequal, outer longer than inner, bases short-appressed, abaxial faces without glutinous ridge, minutely scabridulous, apices green, thick, spreading to curved-ascending, proximally flattened, linear, spines stout, 5–12 mm; outer entire or pinnately spiny, inner entire, scabridulous-ciliolate; apices of inner flexuous, sometimes slightly expanded and minutely erose. Corollas lavender-pink, 20–26 mm, tubes 5–8.5 mm, throats 5.2–8 mm, lobes linear, 9–10 mm; style tips 3.5–4.2 mm, conspicuously exserted beyond corolla lobes. Cypselae dark brown, 4.5–5 mm, apical collars not differeniated; pappi ca. 20 mm.