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Hooker's thistle, white thistle

Texas or Texas purple or southern thistle, Texas thistle

Habit Biennials or monocarpic (sometimes polycarpic?) perennials, 20–150 cm; taprooted. Annuals or biennials, 20–200 cm; taprooted.
Stems

usually 1 and erect, less commonly several and ascending, simple to sparingly short-branched in distal 1/2, variably villous with jointed trichomes, and/or finely arachnoid, or ± glabrate;

branches on distal stems 0–many, short, ascending.

usually single, erect, tomentose to ± glabrate;

branches 0–many, usually restricted to distal part, ascending.

Leaves

blades linear-oblong to elliptic, 5–25 × 1–8 cm, subentire to coarsely dentate or deeply pinnatifid, lobes lance-oblong to broadly triangular, spinulose to spiny-dentate or shallowly lobed, main spines 2–10 mm, abaxial faces usually ± densely gray- or white-tomentose with felted arachnoid trichomes, ± villous to tomentose along major veins with septate trichomes, sometimes glabrous or glabrate, adaxial ± green, glabrous to thinly arachnoid, often ± villous or tomentose with septate trichomes;

basal often present at flowering, spiny winged-petiolate or sessile;

principal cauline well distributed, proximally winged-petiolate, distally sessile, gradually reduced, bases sometimes short-decurrent;

distal ± reduced, often narrower than proximal, sometimes with non-pigmented bases, sometimes pectinately spiny.

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.

Peduncles

0–8+ cm.

slender, 3–30 cm (not overtopped by crowded distal leaves).

Involucres

(green or often purplish), broadly ovoid, 2–3.3 × 1.5–4 cm, loosely to densely villous with septate trichomes to tomentose and/or arachnoid.

ovoid to hemispheric, 1.5–2 × 1.5–2 cm, thinly arachnoid, glabrate.

Corollas

white, ochroleucous, or occasionally pink, 20–28 mm, tubes 10–13 mm, throats 6.5–9 mm, lobes 5–7 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.

Phyllaries

in 4–8 series, imbricate to subequal, bases short-appressed, entire, abaxial faces with or without narrow glutinous ridge, apices stiffly spreading to ascending, linear, long, plane, spines straight, slender, 3–5 mm;

apices of inner flexuous, sometimes expanded and erose.

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.

Heads

1–many, borne singly or crowded in spiciform, racemiform, subcapitate, or sometimes more openly branched corymbiform arrays.

1–many, in openly paniculiform arrays.

Cypselae

dark brown, 5–6.5 mm, apical collars not differentiated;

pappi 18–22 mm.

brown, 3–5 mm, apical collars not differentiated;

pappi 15–16 mm.

2n

= 34.

= 22, 23, 24.

Cirsium hookerianum

Cirsium texanum

Phenology Flowering summer (Jun–Sep). Flowering spring–summer (Apr–Jul).
Habitat Moist soil, grasslands, aspen parkland, forest edges and openings, subalpine, alpine meadows Roadsides, pastures, fields, shrub-tree savannas
Elevation 600–2900 m (2000–9500 ft) 0–1000 m (0–3300 ft)
Distribution
from FNA
ID; MT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AR; LA; MO; NM; OK; TX; Mexico (Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
Discussion

Cirsium hookerianum occurs from the Canadian Coast Ranges of British Columbia east to the northern Cascade Range and the northern Rocky Mountains. The relationship between C. hookerianum, C. kelseyi, which I have tentatively included in C. hookerianum, and C. longistylum needs further investigation. A case could be made for including all three in an expanded concept of C. hookerianum, but more investigation of the variation patterns is needed before this is done. Certainly C. kelseyi is better treated within or as a close ally of C. hookerianum than in C. scariosum (var. scariosum), where R. J. Moore and C. Frankton (1974) synonymized it. Cirsium hookerianum is known to hybridize with C. undulatum.

(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.)

Source FNA vol. 19, p. 148. FNA vol. 19, p. 119.
Parent taxa Asteraceae > tribe Cardueae > Cirsium Asteraceae > tribe Cardueae > Cirsium
Sibling taxa
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms C. kelseyi C. austrinum, C. helleri, C. texanum var. stenolepis
Name authority Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 418. (1841) Buckley: Proc. Acad. Nat. Sci. Philadelphia 13: 460. (1862)
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