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Hooker's thistle, white thistle

Anderson's thistle, rose thistle

Habit Biennials or monocarpic (sometimes polycarpic?) perennials, 20–150 cm; taprooted. Perennials (but often appearing biennial), (15–)40–70(–100) cm; rootstocks producing erect, taprooted caudices and rosettes.
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 1, erect, subglabrous to puberulent and/or tomentose;

branches 0–several, stiffly 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 ± elliptic, 8–35 × 4–8 cm, divided about halfway to midveins, lobes spreading, triangular, coarsely dentate or with a few broad lobes, obtuse to acute, main spines 1–5 mm, abaxial faces green or gray, thinly tomentose, adaxial green and glabrous to sparingly pilose;

basal often present at flowering, spiny winged-petiolate;

main cauline reduced distally, bases clasping;

distal much reduced, linear-oblong, usually less deeply lobed and often spinier than proximal.

Peduncles

0–8+ cm.

0–20 cm.

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.

broadly cylindric to narrowly campanulate, 3–5 × 2–4 cm, loosely arachnoid or ± glabrous, finely short-ciliate.

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.

red to reddish purple, 30–45 mm, tubes 10–20 mm, throats 10–16 mm, lobes 9–11 mm;

style tips 3.5–5 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 6–8 series, imbricate, outer green, inner purple to red, linear-lanceolate (outer) to linear (inner), abaxial faces without glutinous ridge;

outer and mid bodies short, appressed, entire or spinulose-ciliate, apices long-spreading to ascending, entire or spinulose-ciliate or rarely with expanded, fringed appendages, spines straight, weak, 1–3 mm;

apices of inner red to purple, straight or rarely twisted, long, flat, entire.

Heads

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

1–6, borne singly or in corymbiform, racemiform, or spiciform arrays.

Cypselae

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

pappi 18–22 mm.

brown, 6–7 mm, apical collars narrow;

pappi 25–40 mm.

2n

= 34.

= 32, 64.

Cirsium hookerianum

Cirsium andersonii

Phenology Flowering summer (Jun–Sep). Flowering summer (Jul–Sep).
Habitat Moist soil, grasslands, aspen parkland, forest edges and openings, subalpine, alpine meadows Moist to dry soils, openings in montane woodlands, montaine coniferous forests, aspen groves
Elevation 600–2900 m (2000–9500 ft) 1100–2900 m (3600–9500 ft)
Distribution
from FNA
ID; MT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; NV
[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 andersonii grows in the Cascade Range of northern California south through the Sierra Nevada of eastern California and western Nevada. It has been reported from the mountains of southwestern Idaho, but I have not seen specimens from there.

Heads of Cirsium andersonii are actively visited by hummingbirds as well as a variety of insects (P. L. Barlow-Irick 2002).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 19, p. 148. FNA vol. 19, p. 145.
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. 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. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms C. kelseyi Cnicus andersonii
Name authority Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 418. (1841) (A. Gray) Petrak: Bot. Tiddsskr. 31: 68. (1911)
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