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

	upper leaf surface with short stiff bristles
	heads larger, more than 2.5 cm high; NOT [heads small, less than 2.5 cm high]
	involucres more than 2 cm high; NOT [involucres 1-2 cm high]
	bracts of involucre covered with cobwebby hairs
	all bracts spine-tipped; NOT [inner bracts twisted but not spine-tipped]

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

	juice watery; NOT [juice milky]
	leaves with spiny margins
	bracts of involucre NOT dry or parchmenty, usually green
	some bracts spiny tipped; NOT [involucral bracts with hooked bristles]
	receptacle densely bristly; NOT [receptacle naked]
	flower heads with all florets tubular; NOT [flower heads with florets both tubular and ligulate]; NOT [flower heads with all florets ligulate]
	stamens united to form a tube around the pistil
	pappus of capillary bristles; NOT [pappus of scales, or of awns, or a crown or none]
	pappus hairs much longer than achene
	pappus bristles plumose; NOT [pappus bristles naked or merely minutely barbellate or merely roughened]