Cirsium vulgare
 
Bull Thistle

Achene Close-Up

West Block, Cypress Hills Provincial Park
06-Aug-2006

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Vulgare: Answers to key questions in Budd's Flora (BF) and Flora of Alberta (FOA) leading to this species.  
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upper leaf surface with short stiff bristles

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heads larger, more than 2.5 cm high; NOT [heads small, less than 2.5 cm high]

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involucres more than 2 cm high; NOT [involucres 1-2 cm high]

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bracts of involucre covered with cobwebby hairs

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all bracts spine-tipped; NOT [inner bracts twisted but not spine-tipped]

 

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Cirsium: Answers to key questions in Budd's Flora (BF) and Flora of Alberta (FOA) leading to this genus. 
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juice watery; NOT [juice milky]

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leaves with spiny margins

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bracts of involucre NOT dry or parchmenty, usually green

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some bracts spiny tipped; NOT [involucral bracts with hooked bristles]

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receptacle densely bristly; NOT [receptacle naked]

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flower heads with all florets tubular; NOT [flower heads with florets both tubular and ligulate]; NOT [flower heads with all florets ligulate]

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stamens united to form a tube around the pistil

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pappus of capillary bristles; NOT [pappus of scales, or of awns, or a crown or none]

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pappus hairs much longer than achene

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pappus bristles plumose; NOT [pappus bristles naked or merely minutely barbellate or merely roughened]