Rivalis:  Answers to key questions in Budd's Flora and Flora of Alberta leading to this species.   herbs plants not usually glandular plants without runners lower leaves ternate or digitately 5-7 foliate, sometimes pinnate leaflets green below, often hirsute or pilose; NOT densely white or gray tomentose flowers few to many, in terminal cymes; NOT solitary on naked peduncles; NOT from nodes of stolons flowers in a leafy cyme; inflorescence NOT just leafy at base petals yellow petals shorter than sepals; NOT longer than sepals petals minute; NOT large petals cuneate or narrowly obovate; NOT broadly obovate or rounded stamens 5 or 10 style terminal to the ovary or nearly so; NOT nearly basal achenes smooth; NOT somewhat rugulose ribbed; NOT with a corky enlargement on one side

The key to the Rosaceae genera in Flora of Alberta requires that the petals of Potentilla be longer than the sepals; however, they are shorter than the sepals in this species.  Similarly, the same key requires 10 or more stamens, while the key to the Potentilla species in the same flora allows rivalis to have 5 stamens.

 

Potentilla: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus.  These answers do not apply to all species of Potentilla found in the Canadian prairie provinces, but they do apply to this species. herbs, or with a woody base but otherwise herbaceous; NOT shrubs or trees leaves compound, but NOT much dissected into linear lobes basal leaves with more than 3 leaflets calyx lobes 5, alternating with smaller bractlets, together appearing like 10 sepals hypanthium lacking hooked prickles petals usually longer than the sepals; NOT little if any longer than the sepals (FOA) stamens 10 or more; NOT 5 (FOA) carpels 10-many style much shorter than the achene style articulated at base and deciduous from the achene; NOT jointed near the middle; NOT plumose; NOT persisting in fruit carpels becoming achenes, but NOT in a fleshy receptacle (eg. strawberry); carpels NOT becoming druplets (eg. raspberry)

Rosaceae: Answers to key questions in Budd's Flora leading to this family. herbs plants terrestrial or semi-aquatic plants NOT with colored milky juice plants with more than one normal leaf some or all leaves alternate leaves with stipules flowers with two floral rings, and with each petal distinct from the others calyx regular flowers regular in shape stamens usually separate or partly so; NOT united in a column stamens usually numerous; NOT 5 or 10 ovary of one or more carpels; NOT of 5 united carpels