Arvensis: Answers to key questions in Budd's Flora and Flora of Alberta leading to this species. 

	perennials from creeping rootstocks; NOT [annuals growing from deep taproots]
	flowering heads 3-5 cm across; NOT [flowering heads not over 2.5 cm across]
	fruiting involucre 14-24 mm high; NOT [fruiting involucre 9-13 mm high]

Sonchus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 

	juice milky; NOT [juice watery]
	stem not diffusely branched
	plants with at least some cauline leaves; NOT [plants scapose, leaves all basal]
	leaves broader and leaf-like; NOT [leaves narrowly linear or scale-like]
	heads few to many; NOT [heads solitary]
	involucre of 2 or more series; NOT [involucre uniseriate or biseriate] (FOA)
	flowers all ligulate
	flowers all perfect; NOT [flowers pistillate or neuter]
	flowers yellow
	stamens united to form a tube around the pistil (Checked Above)
	achenes flattened, at least twice as wide as thick
	achenes beakless; NOT [achenes beaked, the pappus borne on a disc at the tip]
	pappus well developed, at least in part of capillary bristles; NOT [pappus of minute scales or none]
	pappus not scale-like at the base, entirely of capillary bristles; NOT [pappus scale-like at the base, with plumose terminal bristles]
	pappus simple, consisting of bristles only; NOT [pappus double, the outer ring consisting of 5 small scale-like appendages, the inner ring bristles]
	pappus bristles simple; NOT [pappus bristles plumose]
	pappus white; NOT [pappus brownish]