Cirsium pulcherrimum |
Cirsium texanum |
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Wyoming thistle |
Texas or Texas purple or southern thistle, Texas thistle |
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Habit | Perennials polycarpic, 15–60(–90) cm; deep-seated woody tap-roots and caudices. | Annuals or biennials, 20–200 cm; taprooted. | ||||
Stems | 1–few, erect or ascending, arachnoid-tomentose or ± glabrate; branches 0–5+, usually in distal 1/2, ascending. |
usually single, erect, tomentose to ± glabrate; branches 0–many, usually restricted to distal part, ascending. |
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Leaves | blades linear to oblong, oblanceolate, or elliptic, 5–25 × 0.6–7 cm, unlobed and merely spinulose or spiny-dentate to regularly pinnatifid, lobes 5–8(–many) pairs, well separated, usually with broad, U-shaped sinuses to crowded, linear to triangular-ovate, ascending-spreading to retrorse, merely spinulose to coarsely dentate or few lobed, main spines 2–7 mm, ± slender, abaxial faces gray to white, usually densely arachnoid-tomentose, sometimes ± glabrate, sometimes villous with septate trichomes along veins, adaxial green, glabrous or less commonly thinly to densely gray-tomentose; basal often present at flowering, spiny winged-petiolate; principal cauline well distributed, gradually reduced distally, proximal usually winged-petiolate, mid and distal sessile, bases decurrent as spiny wings 1.5–3.5 cm; distalmost reduced, ± bractlike. |
blades oblong to elliptic, 7–30 × 2–12 cm, unlobed and merely spinulose to irregularly dentate or shallowly to deeply pinnatifid, lobes ± triangular, separated by narrow to wide sinuses, sometimes coarsely dentate or lobed proximally, obtuse to acute, main spines slender to stout, 1–5 mm, abaxial faces arachnoid tomentose, adaxial glabrous or thinly arachnoid; basal often absent at flowering, petioles slender, ± winged; cauline progressively reduced, proximal petiolate, mid and distal broadly sessile, bases ± auriculate-clasping or decurrent 1–3 cm; distalmost linear to lanceolate, bractlike, irregularly dentate or shallowly lobed. |
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Peduncles | 0–15 cm. |
slender, 3–30 cm (not overtopped by crowded distal leaves). |
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Involucres | ovoid to campanulate, 1.8–2.7 × 1–2 cm, thinly arachnoid-tomentose or glabrate. |
ovoid to hemispheric, 1.5–2 × 1.5–2 cm, thinly arachnoid, glabrate. |
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Corollas | pink to purple (creamy white), 18–25 mm, tubes 7–9 mm, throats 5.5–7.5 mm, lobes 4–8 mm; style tips 3–5.5 mm. |
white to pink-purple, 20–25 mm, tubes 7–10 mm, throats 6–8 mm (noticeably wider than tubes), lobes 4–7 mm; style tips 3–4 mm. |
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Phyllaries | in 6–7 series, ± imbricate, green or with dark subapical patch or appendage, linear to linear-lanceolate, margins entire, abaxial faces with narrow glutinous ridge; outer and middle bases appressed, apical appendages spreading to stiffly ascending, linear-lanceolate to acicular, entire, spines spreading or ascending, stout, 2–7 mm, often flattened; apices of inner stiffly erect or sometimes flexuous, narrow, flat. |
in 8–10 series, imbricate, green, lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge; outer and middle appressed, bodies entire, acute, spines spreading, slender, 1–5 mm; apices of inner often flexuous, flat, scabrid-ciliolate, acuminate. |
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Heads | 1–few, borne singly or in 2–3-headed clusters in ± congested flat-topped or racemiform arrays at tips of main stem and branches, sometimes also in distal axils. |
1–many, in openly paniculiform arrays. |
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Cypselae | tan to dark brown, 5–6 mm, apical collars yellow, narrow; pappi 14–16 mm. |
brown, 3–5 mm, apical collars not differentiated; pappi 15–16 mm. |
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2n | = 34. |
= 22, 23, 24. |
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Cirsium pulcherrimum |
Cirsium texanum |
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Phenology | Flowering spring–summer (Apr–Jul). | |||||
Habitat | Roadsides, pastures, fields, shrub-tree savannas | |||||
Elevation | 0–1000 m (0–3300 ft) | |||||
Distribution |
CO; ID; MT; NE; UT; WY
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AR; LA; MO; NM; OK; TX; Mexico (Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas)
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Discussion | Varieties 2 (2 in the flora). Cirsium pulcherrimum is closely related to C. clavatum. In southeastern Wyoming and northern Colorado some plants combine foliage and involucral characters of C. pulcherrimum var. pulcherrimum and C. clavatum var. americanum. The inheritance of these characters needs to be examined at the population level to determine whether the intermediates are hybrids or the products of past introgression or incomplete differentiation. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cirsium texanum ranges from the Chihuahuan Desert regions of trans-Pecos Texas and adjacent southeastern New Mexico across the plains of Texas and southern Oklahoma to southwestern Arkansas and southwestern Louisiana and south into north-central Mexico. D. S. Correll and M. C. Johnston (1970) suggested hybridization between Cirsium texanum and C. undulatum to explain anomalous specimens in the Edwards Plateau and trans-Pecos regions of western Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 125. | FNA vol. 19, p. 119. | ||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Carduus pulcherrimus | C. austrinum, C. helleri, C. texanum var. stenolepis | ||||
Name authority | (Rydberg) K. Schumann: Just’s Bot. Jahresber. 29(1): 566. (1903) | Buckley: Proc. Acad. Nat. Sci. Philadelphia 13: 460. (1862) | ||||
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