View source for Cirsium hookerianum

{{Treatment/ID
|accepted_name=Cirsium hookerianum
|accepted_authority=Nuttall
|publications={{Treatment/Publication
|title=Trans. Amer. Philos. Soc., n. s.
|place=7: 418. 1841
|year=1841
}}
|common_names=Hooker’s or white thistle
|special_status={{Treatment/ID/Special_status
|code=E
|label=Endemic
}}
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Cirsium kelseyi
|authority=(Rydberg) Petrak
|rank=species
}}
|hierarchy=Asteraceae;Asteraceae tribe Cardueae;Cirsium;Cirsium hookerianum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Cardueae]]</div><div class="higher-taxon"><small>genus</small>[[Cirsium]]</div><div class="higher-taxon"><small>species</small>[[Cirsium hookerianum]]</div></div>
|volume=Volume 19
|mention_page=page 100, 101, 102, 121, 126, 149
|treatment_page=page 148
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Biennials </b>or monocarpic (sometimes polycarpic?) perennials, 20–150 cm; taprooted. <b>Stems</b> 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. <b>Leaves</b>: 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. <b>Heads</b> 1–many, borne singly or crowded in spiciform, racemiform, subcapitate, or sometimes more openly branched corymbiform arrays. <b>Peduncles</b> 0–8+ cm. <b>Involucres</b> (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. <b>Phyllaries</b> 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. <b>Corollas</b> 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. <b>Cypselae</b> dark brown, 5–6.5 mm, apical collars not differentiated; pappi 18–22 mm. <b>2n</b> = 34.</span><!--

-->{{Treatment/Body
|phenology=Flowering summer (Jun–Sep).
|habitat=Moist soil, grasslands, aspen parkland, forest edges and openings, subalpine, alpine meadows
|elevation=600–2900 m
|distribution=Alta.;B.C.;Idaho;Mont.;Wash.;Wyo.
|discussion=<p><i>Cirsium hookerianum</i> occurs from the Canadian Coast Ranges of British Columbia east to the northern Cascade Range and the northern Rocky Mountains. The relationship between <i>C. hookerianum</i>, C. kelseyi, which I have tentatively included in <i>C. hookerianum</i>, and <i>C. longistylum</i> needs further investigation. A case could be made for including all three in an expanded concept of <i>C. hookerianum</i>, 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 <i>C. hookerianum</i> than in <i>C. scariosum</i> (<i></i>var.<i> scariosum</i>), where R. J. Moore and C. Frankton (1974) synonymized it. <i>Cirsium hookerianum</i> is known to hybridize with <i>C. undulatum</i>.</p>
|tables=
|references=
}}<!--

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-->{{#Taxon:
name=Cirsium hookerianum
|authority=Nuttall
|rank=species
|parent rank=genus
|synonyms=Cirsium kelseyi
|basionyms=
|family=Asteraceae
|phenology=Flowering summer (Jun–Sep).
|habitat=Moist soil, grasslands, aspen parkland, forest edges and openings, subalpine, alpine meadows
|elevation=600–2900 m
|distribution=Alta.;B.C.;Idaho;Mont.;Wash.;Wyo.
|reference=None
|publication title=Trans. Amer. Philos. Soc., n. s.
|publication year=1841
|special status=Endemic
|source xml=https://bitbucket.org/aafc-mbb/fna-data-curation/src/2e0870ddd59836b60bcf96646a41e87ea5a5943a/coarse_grained_fna_xml/V19-20-21/V19_137.xml
|tribe=Asteraceae tribe Cardueae
|genus=Cirsium
|species=Cirsium hookerianum
}}<!--

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