Palustris: Answers to questions in Lee/Harmes key leading to this species. 

	rootstalk slender; NOT [rootstalk thick]
	runners present; NOT [runners absent]
	plant without leafy flowering stems, the leaf and flower stems all arise directly from a central rootstalk; NOT [plant with leafy flowering stems]
	plants glabrous; NOT [some leaves with hairy petioles]
	leaves not deeply divided or lobed, merely shallowly toothed; NOT [leaves cleft almost to their bases]
	flowers pale mauve; NOT [flowers blue-purple], NOT [flowers yellow], NOT [flowers white]
	NOT [flower spur is long, about 2/3 the length of the petal blade]
	side petals or all petals bearded; NOT [petals beardless]

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

	herbs; NOT [shrubs or trees]
	plants terrestrial or semiaquatic; NOT [plants aquatic, leaves submerged or floating]
	plants not with colored milky juice
	plants with more than one normal leaf
	some or all leaves alternate; NOT [leaves opposite, whorled, or basal]
	leaves with stipules; NOT [leaves without stipules, or having glands]
	flowers with two floral rings
	calyx regular; NOT [calyx irregular, some sepals smaller than others]
	corolla with each petal distinct from the others
	corolla irregular in shape; NOT [corolla regular in shape]
	corolla with one petal spurred or sac-like; NOT [corolla pea-like]
	stamens usually separate or partly so, not in a column; NOT [stamens numerous, united into a column]
	fruit a 3-valved capsule; NOT [fruit a legume]