Cirsium muticum |
Cirsium joannae |
|
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chardon mutique, dunce-nettle, horsetops, swamp thistle |
Joanna's thistle |
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Habit | Biennials, 30–230 cm; taproots fleshy. | Perennials, 100–150 cm; caudices taprooted. |
Stems | single, erect, villous with septate trichomes or glabrate, distally sometimes thinly tomentose; branches few–many, ascending. |
1, fleshy, erect, openly branched in distal 1/2, glabrous; branches on distal stems several, ascending. |
Leaves | ovate to broadly elliptic or obovate, 15–55 × 4–20 cm, deeply pinnatifid, to 7/8 to midribs, lobes linear to lanceolate, acute to acuminate, irregularly few toothed or lobed, main spines 2–3 mm, abaxial faces thinly tomentose or glabrate, villous with septate trichomes on the veins, adaxial faces thinly pilose; basal usually absent at flowering, petioles spiny-winged, bases tapered; principal cauline petiolate or sessile, gradually reduced distally, bases sometimes ± clasping, not decurrent; distal cauline bractlike with narrowly linear lobes, often spinier than the proximal. |
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. |
Peduncles | 0–15 cm (sometimes overtopped by distal cauline leaves, not subtended by involucre-like ring of bracts). |
0–2 cm Involucres green, ovoid to campanulate (not including spreading phyllary apices), 2.5–4 × 2.5–3.5 cm, appearing glabrous. |
Involucres | ovoid to broadly cylindric or campanulate, 1.7–3 × 1–3 cm, arachnoid. |
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Corollas | lavender or purple (white), 16–32 mm, tubes 7–15 mm, throats 4.5–10 mm (noticeably wider than tubes), lobes 4–8 mm; style tips 3.5–5 mm. |
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. |
Phyllaries | in 8–12 series, strongly imbricate, dull green with darker subapical patch, ovate (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge, outer and middle appressed, bodies minutely spinulose, apices obtuse to acute, spines erect (sometimes appearing as spreading in dry specimens), 0–0.5 mm; apices of inner phyllaries straight or ± flexuous, flattened. |
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. |
Heads | 1–many in ± open corymbiform or paniculiform arrays. |
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. |
Cypselae | dark brown, 4.5–5.5 mm, apical collars yellow, 0.3 mm; pappi 12–20 mm. |
dark brown, 4.5–5 mm, apical collars not differeniated; pappi ca. 20 mm. |
2n | = 20, 21, 22, 23, 30. |
|
Cirsium muticum |
Cirsium joannae |
|
Phenology | Flowering summer (Jul–Sep). | Flowering summer (Aug–Sep). |
Habitat | Wet soil in meadows, prairies, marshes, swamps, bogs, open woods | Hanging gardens with Lobelia, Abies, and Adiantum |
Elevation | 0–1500+ m (0–4900+ ft) | 1700 m (5600 ft) |
Distribution |
AL; AR; CT; DE; FL; GA; IA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; NC; ND; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; MB; NB; NL; NS; ON; PE; QC; SK; SPM
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UT |
Discussion | Cirsium muticum is very widely distributed across the eastern half of North America from the prairies of southeastern Saskatchewan across southern Canada to Newfoundland and south in the United States from North Dakota and Maine to southeastern Texas and northern Florida. It is more common in the northern half of this range and extends from the coastal plain to the Appalachian highlands. The widely scattered populations in coastal lowlands in the southern United States may be relicts of the glacial distribution of the species. Cirsium muticum is known to hybridize with C. discolor (discussed thereunder) and C. flodmanii. Draining and modification of wetlands have affected populations of C. muticum in some areas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 113. | FNA vol. 19, p. 163. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus muticus, C. muticum var. monticola | |
Name authority | Michaux: Fl. Bor.-Amer. 2: 89. (1803) | S. L. Welsh: in S. L. Welsh et al., Utah Fl. ed. 3, 168. (2003) |
Web links |