Cirsium vulgare
 
Bull Thistle

Achene

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

bullet

Vulgare: Answers to key questions in Budd's Flora (BF) and Flora of Alberta (FOA) leading to this species.  
bullet

upper leaf surface with short stiff bristles

bullet

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

bullet

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

bullet

bracts of involucre covered with cobwebby hairs

bullet

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

 

bullet

Cirsium: Answers to key questions in Budd's Flora (BF) and Flora of Alberta (FOA) leading to this genus. 
bullet

juice watery; NOT [juice milky]

bullet

leaves with spiny margins

bullet

bracts of involucre NOT dry or parchmenty, usually green

bullet

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

bullet

receptacle densely bristly; NOT [receptacle naked]

bullet

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

bullet

stamens united to form a tube around the pistil

bullet

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

bullet

pappus hairs much longer than achene

bullet

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