Cirsium ochrocentrum |
Cirsium pitcheri |
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Beaumont thistle, yellowspine thistle |
dune thistle, Pitcher's thistle, sand-dune thistle |
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Habit | Perennials, 30–90 cm; crown sprouts or runner roots producing adventitious buds. | Biennials or short-lived monocarpic perennials, 20–100 cm; taproots long. | ||||
Stems | 1–20+, erect or ascending, densely gray-tomentose with non-septate trichomes; branches 0 or few, usually in distal 1/2, ascending. |
1 or few, erect, densely gray-tomentose; branches 0 to several, ascending to spreading. |
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Leaves | blades oblong to narrowly elliptic, 10–30 × 2–8 cm, strongly undulate, margins coarsely dentate or shallowly to deeply pinnatifid with 8–15 pairs of lobes 0.5–2 cm, often revolute, lobes ± triangular, closely spaced, spreading, spinose-dentate and cleft into 2–5 spine-tipped divisions, main spines 5–20 mm, yellowish, abaxial faces densely white-tomentose, adaxial thinly gray-tomentose; basal usually present at flowering, winged-petiolate; principal cauline sessile, progressively reduced distally, bases ± auriculate to long-decurrent as spiny wings; distal cauline usually much reduced, less lobed. |
blades elliptic to obovate, 10–30 × 8–14 cm, deeply divided nearly to midveins, lobes ascending to spreading, linear, remote, margins revolute, entire or minutely spinulose, main spines 1–2 mm, faces gray-tomentose, more densely so abaxially; basal present or withered at flowering, petiolate; principal cauline well distributed, bases decurrent as linear-lobed to spiny wings 1–3 cm; distal cauline well developed. |
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Peduncles | 0–4 cm. |
0–5 cm. |
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Involucres | ovoid to hemispheric or broadly campanulate, 2.5–4.5 × 2.5–4.5 cm in first-formed heads, often smaller in later ones, loosely arachnoid on phyllary margins or glabrate. |
ovoid to campanulate, 2–3 × 2–3 cm, loosely arachnoid on phyllary margins or glabrate. |
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Corollas | white or pale lavender to purple, pink, or red, 25–45 mm, tubes 8–25 mm, throats 6–17 mm, lobes 6–15 mm; style tips 2–8 mm. |
dull white or pinkish-tinged (rarely rich purple), 20–30 mm, tubes 8.5–15 mm, throats 4.5–10 mm, lobes 3–8 mm; style tips 3.5–5.5 mm. |
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Phyllaries | in 5–10 series, imbricate, ovate (outer) to linear-lanceolate (inner), margins entire, abaxial faces with narrow glutinous ridge; outer and middle appressed, spines spreading, 3–12 mm; apices of inner often flexuous, expanded and flat, scabrid-margined, sometimes erose, spineless. |
in 6–8 series, imbricate, ovate-lanceolate (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge; outer and middle appressed, acute, spines ascending to spreading, slender, 1–2(–3) mm; apices of inner often flexuous, flattened, spineless, scabrid. |
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Heads | 1–few, in leafy, ± corymbiform arrays. |
1–20+ in corymbiform arrays. |
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Cypselae | light brown, sometimes with lighter or darker streaks, 6–9 mm, apical collars colored like the body, narrow; pappi (white or tawny), 20–40 mm, usually noticeably shorter than corolla. |
light brown, sometimes with darker streaks, 6–7.5 mm, apical collars lighter colored, very narrow; pappi 15–30 mm, usually noticeably shorter than corolla. |
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2n | = 30, 31, 32, 34. |
= 34. |
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Cirsium ochrocentrum |
Cirsium pitcheri |
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Phenology | Flowering spring–summer (May–Sep). | |||||
Habitat | Sand dunes and beaches | |||||
Elevation | 180–200 m (600–700 ft) | |||||
Distribution |
AZ; CA; CO; KS; NE; NM; OK; SD; TX; UT; WY; n Mexico
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IL; IN; MI; WI; ON
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Discussion | Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cirsium pitcheri is endemic to beach and dune habitats around lakes Huron, Michigan, and Superior. It has been extirpated from portions of its former range at the southern end of Lake Michigan. It is threatened by foot traffic, off-road vehicular activity, and clearing and development of beachside habitats. It is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 123. | FNA vol. 19, p. 122. | ||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Cnicus pitcheri | |||||
Name authority | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 110. (1849) | (Torrey ex Eaton) Torrey & A. Gray: Fl. N. Amer. 2: 456. (1843) | ||||
Web links |