Najadaceae: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan, Fascicle 6, Flora of Saskatchewan by Anna Leighton leading to this family. 

	Plants larger and with well-defined stems and/or leaves; NOT [Plants free-floating aquatics growing on the surface or suspended in water, solitary and 0.5-15 mm across or attached together in larger colonies; identifiable stems and leaves absent]
	Plants growing in water (aquatic) with stems, leaves and inflorescences growing underwater (submersed) or floating on the surface, sometimes with inflorescences somewhat elevated above the water (emergent); all leaves cauline, none basal; NOT [Plants growing on land (terrestrial) or in wetlands (paludal) with upper parts of stems, leaves and inflorescences growing well above the water surface (emergent), or if plants aquatic and submersed, then all or at least some leaves basal]
	Flowers and fruit not as below, either female flowers solitary in leaf axils have solitary fruit, or the flowers are perfect and 2-many in terminal or axillary spikes; blades various; NOT [Female flowers solitary in leaf axils with 4-5, short-stalked, beaked fruit with  dentate convex margins; leaf blades linear, 0.2-1 mm wide, 3.5-4.2 cm long]
	Flowers and fruit solitary in leaf axils at stem nodes; leaves submersed, sessile, 0.5-3 cm long, opposite or whorled; stipules absent; NOT [Flowers 2 or more in terminal or axillary spikes; leaves submersed or floating, sessile or petiolate, often > 3 cm long, usually alternate with the pair under inflorescences nearly opposite; stipules forming sheaths enveloping stems, but often breaking down with age]
	Leaves linear from a wide sheathing base that encloses flowers and fruit; widest leaves to ca.1 mm wide above base; leaf margins with reddish, spiny, forward-facing teeth; flowers not enclosed in a spathe; pollination and fruit maturation both in leaf axils; perianth absent; NOT [Leaves linear, oblong to ovate or narrowly elliptic with bases not widened; widest leaves usually >= 2 mm wide; leaf margins with minute teeth; each flower enclosed in a spathe arising in leaf axils and elevated on a stalk to reach the water surface for pollination with the fruit developing in the leaf axil; perianth of 3 sepals and 3 white petals]