Bur Buttercup, Hornseed, Hornseed Buttercup: Ceratocephala testiculata (Synonyms: Ceratocephalus orthoceras, Ranunculus testiculatus) -
Tall Buttercup, Meadow Buttercup: Ranunculus acris (Synonym: Ranunculus acris var. latisectus) -
Dwarf Plantainleaved Buttercup, Dwarf Plantain-leaved Buttercup, Plantainleaf Buttercup: Ranunculus alismifolius var. alismellus (Synonym: Ranunculus alismaefolius var. alismellus) -
Water Plantain Buttercup, Plantain-leaved Buttercup: Ranunculus alismifolius var. alismifolius (Synonym: Ranunculus alismaefolius var. alismaefolius) -
Davis' Buttercup, Plantain-leaved Buttercup, Water-plantain Buttercup: Ranunculus alismifolius var. davisii (Synonym: Ranunculus alismaefolius var. davisii) -
Hartweg's Buttercup: Ranunculus alismifolius var. hartwegii (Synonym: Ranunculus alismaefolius var. hartwegii) -
Pink Buttercup, Anderson's Buttercup: Ranunculus andersonii (Synonym: Beckwithia andersonii) -
Leafy Water Buttercup, White Water Buttercup, White Water Crowfoot: Ranunculus aquatilis var. aquatilis (Synonyms: Ranunculus aquatilus var. hispidulus, Ranunculus trichophyllus var. hispidulus) -
Threadleaf Crowfoot, Water Buttercup, White Water Buttercup, White Water Crowfoot: Ranunculus aquatilis var. diffusus (Synonyms: Ranunculus aquatilis var. caespitosus, Ranunculus aquatilis var. capillaceus, Ranunclus aquatilis var. porteri, Ranunculus aquatilis var. subrigidus, Ranunculus aquatilis var. trichophyllus, Ranunculus longirostris, Ranunculus subrigidus, Ranunculus trichophyllus, Ranunculus trichophyllus var. trichophyllus) -
Corn Buttercup, Field Buttercup, Hungerweed: Ranunculus arvensis (Synonym: Ranunculus arvensis var. tuberculatus) -
Alkali Buttercup, Seaside Buttercup, Shore Buttercup: Ranunculus cymbalaria (Synonym: Halerpestes cymbalaria, Ranunculus cymbalaria var. alpinus, Ranunculus cymbalaria var. saximontana, Ranunculus cymbalaria var. saximontanus) -
Eschscholtz's Buttercup, Snow Buttercup, Subalpine Buttercup: Ranunculus eschscholtzii var. eschscholtzii (Synonyms: Ranunculus eschscholtzii var. typicus, Ranunculus nivalis var. eschscholtzii) -
Snow Buttercup, Suksdorf's Buttercup, Timberline Buttercup: Ranunculus eschscholtzii var. suksdorfii (Synonym: Ranunculus suksdorfii) -
Snow Buttercup, Threesection Buttercup: Ranunculus eschscholtzii var. trisectus (Synonyms: Ranunculus suksdorfii ssp. trisectus, Ranunculus trisectus) -
Yellow Water-buttercup: Ranunculus flabellaris (Synonym: Ranunculus delphiniifolius) -
Creeping Buttercup, Creeping Speerwort, Lesser Spearwort, Small Creeping Buttercup: Ranunculus flammula (Synonyms: Ranunculus filiformis, Ranunculus filiformis var. ovalis, Ranunculus flammula, Ranunculus flammula var. filiformis, Ranunnculus flammula var. flammula, Ranunculus flammula var. ovalis, Ranunculus flammula var. reptans, Ranunculus flammula var. samolifolius, Ranunculus reptans var. ovalis) -
Elliptical Buttercup, Sagebrush Buttercup: Ranunculus glaberrimus var. ellipticus (Synonyms: Ranunculus ellipticus, Ranunculus glaberrimus var. buddii) -
Sagebrush Buttercup, Wax Buttercup: Ranunculus glaberrimus var. glaberrimus (Synonym: Ranunculus glaberrimus var. typicus) -
Arctic Buttercup, Modest Buttercup: Ranunculus grayi (Synonyms: Ranunculus gelidus var. grayi, Ranunculus verecundus) - ?
Downy Buttercup: Ranunculus hebecarpus -
Macoun's Buttercup: Ranunculus macounii (Synonyms: Ranunculus macounii var. macounii, Ranunculus macounii var. oreganus) -
Western Buttercup: Ranunculus occidentalis var. dissectus -
Western Buttercup: Ranunculus occidentalis var. howellii ? -
Western Buttercup, Showy Buttercup: Ranunculus occidentalis var. occidentalis (Synonyms: Ranunculus occidentalis var. dissectus, Ranunculus occidentalis var. eisenii, Ranunculus occidentalis var. howellii, Ranunculus occidentalis var. occidentalis, Ranunculus occidentalis var. rattanii, Ranunculus occidentalis var. ultramontanus) -
Blue Mountain Buttercup: Ranunculus oresterus -
Bloomer's Buttercup, Swamp Buttercup: Ranunculus orthorhynchus var. bloomeri (Synonym: Ranunculus bloomeri) -
Bird's Foot Buttercup, Straightbeak Buttercup, Straight-beak Buttercup, Swamp Buttercup, Western Swamp Buttercup: Ranunculus orthorhynchus var. orthorhynchus (Synonyms: Ranunculus orthorhynchus ssp. alaschensis, Ranunculus orthorhynchus var. alaschensis, Ranunculus orthorhynchus var. hallii) -
Large-flowered Swamp Buttercup, Swamp Buttercup: Ranunculus orthorhynchus var. platyphyllus (Synonym: Ranunculus orthorhynchus ssp. platyphyllus) -
Blue Mountain Buttercup, Mountain Buttercup, Popular Buttercup: Ranunculus populago -
Creeping Buttercup, Double-flowered Creeping Buttercup: Ranunculus repens (Synonyms: Ranunculus repens var. erectus, Ranunculus repens var. glabratus, Ranunculus repens var. pleniflorus, Ranunculus repens var. repens) -
Blister Buttercup, Cursed Buttercup, Celery-leaved Buttercup, Celeryleaved Buttercup, Division Blister Buttercup: Ranunculus sceleratus var. multifidus (Synonym: Ranunculus sceleratus ssp. multifidus) -
Blister Buttercup, Celery-leaved Buttercup: Ranunculus sceleratus var. sceleratus (Synonyms: Hecatonia scelerata, Ranunculus sceleratus var. typicus) -
Little Buttercup, Woodland Buttercup: Ranunculus uncinatus (Synonyms: Ranunculus bongardii, Ranunculus bongardii var. bongardii, Ranunculus bongardii var. tenellus, Ranunculus occidentalis var. parviflorus, Ranunculus uncinatus var. parviflorus, Ranunculus uncinatus var. unciniatus) -