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

	plants herbaceous; NOT [plants suffrutescent], NOT [plants without brown woody stems]
	plants with leafy stems; NOT [plants lacking leafy stems, leaves forming a rosette]
	plants usually much-branched
	stems taller; NOT [stems 3-10 cm tall]
	stems stout; NOT [stems slender]
	stems white with shreddy bark; NOT [stems green or reddish]
	buds nodding; NOT [buds erect]
	flowers larger; NOT [flowers minute]
	flowers white or pinkish; NOT [flowers yellow]
	stigma deeply 4-cleft

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

	hypanthium prolonged beyond the ovary
	flower parts in 4’s; NOT [flower parts in 2’s]
	sepals commonly reflexed; NOT [sepals erect]
	petals yellow, white or pink; NOT [petals purplish]
	anthers attached near their middle, usually versatile; NOT [anthers attached near their base, erect]
	ovary 4-loculed; NOT [ovary2-loculed]
	fruit a capsule; NOT [fruit nut-like]
	fruit opening by valves; NOT [fruit indehiscent]
	fruit opening with 4 valves; NOT [capsules opening with 2 valves]
	fruit NOT covered with hooks; NOT [fruit covered with hooked bristles]
	seeds lacking a coma; NOT [seeds with a tuft of hairs (coma) at one end]
	fruit many-seeded; NOT [fruit 1-seeded]

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

	herbs; NOT [shrubs or trees]
	plants terrestrial; NOT [plants aquatic; leaves submerged or floating], NOT [mud plants with small axillary flowers]
	plants NOT with colored milky juice
	plants with more than one normal leaf
	leaves without stipules, or having glands; NOT [leaves with stipules]
	plants without large petal-like bracts; NOT [plants with an involucre of 4 petal-like bracts]
	flowers with two floral rings
	parts of flowers in twos or fours; NOT [parts of flowers mostly in fives]
	calyx regular; NOT [calyx irregular, some sepals smaller than others]
	each petal distinct from the others
	stamens 10 or fewer; NOT [stamens usually more than 10]
	styles single; NOT [styles 2 or more]
	ovary inferior; NOT [ovary superior]