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Suisun Thistle

Cirsium hydrophilum (Greene) Jepson

Description

provided by eFloras
Biennials or monocarpic perennials, 100–220 cm; taprooted. Stems 1–several, erect, (hollow), openly branched distally or throughout, thinly arachnoid with fine, non-septate trichomes, glabrate. Leaves: blades elliptic to broadly oblanceolate, 10–40+ cm, pinnatifid 1/2–2/3 distance to midveins, larger usually with broad sinuses, lobes broad, few lobed or dentate, main spines 2–9 mm, abaxial faces ± gray-tomentose, sometimes ± glabrate, adaxial thinly arachnoid-tomentose, soon glabrescent; basal present or withered at flowering, winged-petiolate; principal cauline sessile, progressively reduced distally, bases auriculate-clasping or shortly decurrent; distal cauline reduced, bractlike, often spinier than proximal. Heads borne singly or few at branch tips, sometimes subtended by clustered, ± leafy bracts, collectively forming ± open, many-headed paniculiform arrays. Peduncles 0–10+ cm. Involucres ovoid to campanulate, 1.5–2.5 × 1.5–3 cm, thinly arachnoid, glabrate. Phyllaries in 6–9 series, imbricate, dark green to brownish, lanceolate (outer) to linear (inner), abaxial faces with narrow glutinous ridge; outer and middle appressed, apices spreading, finely serrulate, spines slender, 1–2 mm; apices of inner erect, ± flexuous. Corollas pale rose-purple, 18–23 mm, tubes 8–10 mm, throats 5–6 mm, lobes 5–7 mm; style tips 3.5–4.5 mm. Cypselae dark brown to black, 4–5 mm, collars very narrow, stramineous; pappi ca. 15 mm. 2n = 32.
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cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 19: 103, 108, 132 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
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eFloras

Synonym

provided by eFloras
Carduus hydrophilus Greene, Proc. Acad. Nat. Sci. Philadelphia 44: 358. 1893; Cirsium vaseyi (A. Gray) Jepson var. hydrophilum (Greene) Petrak
license
cc-by-nc-sa-3.0
copyright
Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
bibliographic citation
Flora of North America Vol. 19: 103, 108, 132 in eFloras.org, Missouri Botanical Garden. Accessed Nov 12, 2008.
source
Flora of North America @ eFloras.org
editor
Flora of North America Editorial Committee
project
eFloras.org
original
visit source
partner site
eFloras