Pyrifolia: Answers to key questions in Conifers & Catkin-Bearing Trees and Shrubs of Saskatchewan, Fascicle 5, Flora of Saskatchewan by Anna Leighton leading to this species. The answers are in the order you would normally work through the key. 

	Catkins usually flowering as leaves emerge, sometimes just before leaves emerge or throughout the season, subtended by small green leaves of the flowering branchlet that supports them.  NOT  [Catkins usually flowering before leaves emerge, borne directly on bare branches (sessile) and subtended by 1 - 3 short, greenish or brownish, caducous bract-like leaves]
	Low to tall shrubs or trees; not confined to subarctic regions.  NOT [Dwarf shrubs <= 0.15 m (15 cm) tall; subarctic regions]
	Shrubs, usually with several stems; ovaries glabrous or hairy.   NOT  [Trees, with a single trunk, or with several trunks of tree stature; ovaries glabrous]
	NOT [Plants flowering as leaves emerge or throughout the season, often bearing branched catkins; leaf blades linear or strap-shaped, 9 ? 14 ? 24 times longer than wide, up to 11 mm wide with margins remotely spinulose-serrulate, the teeth widely spaced; hairs on leaves white, ferruginous hairs lacking; plants forming extensive colonies by root shoots]
	Petioles without glandular dots or lobes at distal end, or with occasional, inconspicuous dots; floral bracts not as above, if conspicuous and pale, then not deciduous.  NOT [Petioles with glandular dots or lobes at distal end; floral bracts pale tawny, 1.2 ? 4 mm, conspicuous during flowering, deciduous after flowering]
	Ovaries glabrous. NOT [Ovaries hairy].
	Lower surfaces of leaf blades glaucous, sometimes obscured by dense hairs. NOT [Lower surfaces of leaf blades not glaucous, usually glabrous but sometimes hairy.]
	Catkins slender or stout, 16 - 85 mm, styles usually measurable (0.2 ? 0.6 mm); ovaries rarely reddish; leaf blade upper surfaces not glaucous, margins toothed or sinuate; plants to 7 m tall. NOT [Catkins stout to subglobose, 11 - 32 mm; styles immeasurably short (0.1  - 0.24 mm); ovaries often reddish; leaf blade upper surfaces glaucous, margins entire; plants to 2 m tall.]
	Branches red-brown; capsules 7 - 8 mm; leaf blades 1.5 ? 2 ? 3 times longer than wide, upper surfaces often highly glossy; buds and leaves with balsam-like fragrance detectable by some people. NOT [Branches yellow-gray, yellow, yellow-brown or gray-brown; capsules 2.5 ? 6 mm; leaf blades 2.5 ? 3.5 ? 7 times longer than wide, upper surfaces dull or shiny; buds and leaves without balsam-like fragrance.]

Salix: Answers to key questions in Conifers & Catkin-Bearing Trees and Shrubs of Saskatchewan, Fascicle 5, Flora of Saskatchewan by Anna Leighton leading to this genus. 

	shrubs or trees; NOT [trees]
	buds covered by 1 scale; NOT  [buds covered by 3-10 scales]
	buds scale not resinous; NOT [bud scale usually resinous]
	catkins sessile or terminating flowering branchlets; NOT [catkins sessile]
	catkins erect, spreading, or +/- pendulous; NOT [catkins pendulous]
	floral bracts entire, erose, bifid, or irregularly toothed; NOT [floral bracts deeply cut]
	perianth reduced to an adaxial nectary (rarely also an abaxial nectary, then the 2 nectaries distinct or connate into a shallow cup); NOT [perianth reduced to a non-nectariferous, cup-shaped or shallow saucer-shaped floral disc]
	stamens 1, 2, or 3 ? 10; NOT [stamens 6 ? 60 (70)]
	capsules obclavate to ovoid or ellipsoid; NOT [capsules narrowly ovoid to spherical, with the floral disc persistent at base]
	capsules 2-valved; NOT [capsules 2 - 4 valved]

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

	shrubs or trees; NOT [herbs]
	flowers with only one floral ring, with sepals but not petals
	male flowers, at least, in catkins or aments; NOT [flowers not in catkins or aments]
	seeds each with a tuft of hairs; NOT [seeds without a tuft of hairs]