Aparine: Answers to key questions in Budd's Flora and Flora of Alberta leading to this species.  Note that Flora of Alberta separates G. aparine from G. spurium.  However, I am including both of them in G. aparine. Therefore I am excluding (from the list below) answers that separate these two taxa.

	plants annual; NOT [plants perennial]
	internodes glabrous, the angles mostly retrorsely scabrous, at least below; NOT [internodes puberulent, the angles not retrorsely scabrous]
	leaves mostly in whorls of 8; NOT [leaves mostly in whorls of 6], NOT [leaves in whorls of 4]
	leaves linear-lanceolate to narrowly oblanceolate; NOT [leaves elliptic], NOT [leaves linear]
	leaves more than 4 times longer than wide; NOT [leaves generally 3-4 times longer than wide]
	leaves usually 2-3 mm wide; NOT [leaves usually more than 3 mm wide]
	leaves NOT strongly revolute
	ovary and fruit bristly or hairy; NOT [ovary and fruit glabrous]

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

	stems square
	leaves whorled; NOT [leaves opposite]
	inflorescence of open cymes; NOT [inflorescence a head, subtended by bracts]
	corolla rotate; NOT [corolla slender-funnelform]

Rubiaceae: Answers to key questions in Budd's Flora  leading to this family. 

	herbs; NOT [shrubs or trees]
	plants green or with some chlorophyll; NOT [plants parasitic or saprophytic, with chlorophyll]
	plants without milky juice; NOT [plants often with milky juice]
	not climbing plants; NOT [climbing plants with tendrils]
	leaves opposite; NOT [leaves basal or alternate]
	leaves with stipules, appearing whorled; NOT [leaves without stipules]
	flowers NOT in heads or spikes; NOT [flowers in long or short spikes], NOT [flowers in heads or in form resembling a head]
	flowers with two floral rings, but with the petals wholly or partly united forming a tube or bell]
	stamens 4 or 5; NOT [stamens 3]
	ovary inferior; NOT [ovary superior]