Cirsium engelmannii |
Cirsium ochrocentrum |
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blackland thistle, Engelmann's thistle |
Beaumont thistle, yellowspine thistle |
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Habit | Biennials or monocarpic perennials, 40–200 cm; taproots and clusters of coarse fibrous roots that often have tuberlike thickenings. | Perennials, 30–90 cm; crown sprouts or runner roots producing adventitious buds. | ||||
Stems | single, erect, often branched above middle, thinly arachnoid-tomentose, ± glabrate; branches few, ascending. |
1–20+, erect or ascending, densely gray-tomentose with non-septate trichomes; branches 0 or few, usually in distal 1/2, ascending. |
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Leaves | blades elliptic or ovate, 5–20 × 1–10 cm, usually deeply pinnatifid, lobes narrowly to broadly triangular, sinuses broad, rounded (basal and distal cauline sometimes less divided, lobes linear-lanceolate), margins revolute, spreading, entire or spinulose to remotely few-toothed or sharply lobed, main spines slender, 1–5 mm, abaxial faces white-tomentose, adaxial green, villous with septate trichomes or glabrate; basal usually absent at flowering, winged-petiolate, bases tapered; principal cauline well distributed, gradually reduced, bases narrowed, sometimes weakly clasping; distal reduced, widely separated, distalmost bractlike. |
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. |
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Peduncles | 2–20+ cm, essentially naked with much reduced bracts. |
0–4 cm. |
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Involucres | ovoid to broadly cylindric or campanulate, 2.5–3.5 × 2–3 cm, thinly arachnoid. |
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. |
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Corollas | pink to purple (white), 32–38 mm, tubes 15–20 mm, throats 6–9 mm, lobes 8–11 mm; style tips 5–6 mm. |
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. |
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Phyllaries | in 10–12 series, strongly imbricate, greenish with subapical darker central zone, ovate (outer) to lanceolate (inner), abaxial faces with narrow glutinous ridge; outer and middle entire, bodies appressed, spines abruptly spreading to deflexed, slender, 2–4 mm; apices of inner phyllaries narrow, flexuous, flattened, entire or finely erose. |
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. |
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Heads | 1–10+, borne at tips of main stem and branches. |
1–few, in leafy, ± corymbiform arrays. |
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Cypselae | brown, 5–6 mm, apical collars yellow, ca. 1 mm; pappi 25–30 mm. |
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. |
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2n | = 18 (as C. terrae-nigrae), 20 + 1B. |
= 30, 31, 32, 34. |
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Cirsium engelmannii |
Cirsium ochrocentrum |
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Phenology | Flowering spring–summer (May–Jul). | |||||
Habitat | Tallgrass prairies, old fields, roadsides, oak savannas, forest edges, in calcareous clay or rarely sandy soils | |||||
Elevation | 50–200 m (200–700 ft) | |||||
Distribution |
LA; OK; TX |
AZ; CA; CO; KS; NE; NM; OK; SD; TX; UT; WY; n Mexico
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Discussion | Cirsium engelmannii occurs mostly in the blackland prairies of eastern Texas. It ranges northward into southeastern Oklahoma and eastward to northwestern Arkansas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 117. | FNA vol. 19, p. 123. | ||||
Parent taxa | ||||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | C. virginianum var. filipendulum, C. terrae-nigrae | |||||
Name authority | Rydberg: Fl. Rocky Mts., 1069. (1917) | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 110. (1849) | ||||
Web links |