Pumila: Answers to key questions in Flora of the Great Plains leading to this species. 

	flowers nearly sessile or short pedicelled; NOT [flowers with slender pedicels]
	flowers NOT drooping
	samaras suborbicular to broadly elliptic; NOT [samaras elliptical, ovate to oblong]
	samaras NOT densely ciliolate-fringed on each margin

Ulmus: Answers to key questions in Budd's Flora leading to this genus. 

	leaves with a single midrib; NOT [leaves with 2 prominent veins beside the midrib]
	fruit a thin, broadly winged samara; NOT [fruit a drupe with large stone]

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

	trees; NOT [shrubs], NOT [herbs]
	plants with erect stems; NOT [plants with decumbent stems]
	plants NOT climbing
	stipules present
	leaves simple; NOT [leaves pinnately compound]
	leaves wider; NOT [leaves linear, 2.5-7 mm long]
	leaves deciduous; NOT [leaves everygreen]
	flowers appearing BEFORE leaves
	flowers NOT in catkins or aments; NOT [male flowers, at least, in catkins or aments]
	fruit WITHOUT a feathery style; NOT [fruit with a persistent feathery style]
	fruit dry when ripe; NOT [fruit fleshy when ripe]