Lesser Celandine: Ficaria verna (Synonyms: Ranunculus ficaria, Ranunculus ficaria ssp. bulbifera, Ranunculus ficaria ssp. calthifolilus, Ranunculus ficaria var. bulbifera) -
Meadow Buttercup, Tall Buttercup: Ranunculus acris (Synonym: Ranunculus acris var. latisectus) -
Dwarf Plantain-leaved Buttercup, Dwarf Plantainleaved Buttercup: Ranunculus alismifolius var. alismellus (Synonym: Ranunculus alismaefolius var. alismellus) -
Plantain-leaved Buttercup: Ranunculus alismifolius var. alismifolius (Synonym: Ranunculus alismaefolius var. alismaefolius) -
Hartweg's Buttercup: Ranunculus alismifolilus var. hartwegii (Synonyms: Ranunculus alismaefolius var. hartwegii, Ranunculus hartwegii) - Only found west of the Cascade Mountains on the Siskiyou Crest.
Leafy Water Buttercup, White Water Buttercup: Ranunculus aquatilis var. aquatilis (Synonyms: Ranunculus aquatilis var. hispidulus, Ranunculus trichophyllus var. hispidulus) -
Water Buttercup: Ranunculus aquatilis var. diffusus (Synonyms: Ranunculus aquatilis var. capillaceus, Ranunculus aquatilis var. porteri, Ranunculus aquatilis var. subrigidus, Ranunculus lonirostris, Ranunculus subrigidus, Ranunculus trichophyllus) -
Corn Buttercup, Field Buttercup, Hungerweed: Ranunculus arvensis (Synonym: Ranunculus arvensis var. tuberculatus) -
Southern Oregon Buttercup: Ranunculus austro-oreganus (Synonym: Ranunculus austrooreganus) -
Carter's Buttercup: Ranunculus bonariensis var. trisepalus -
Bulbous Buttercup: Ranunculus bulbosus -
California Buttercup: Ranunculus californicus (Synonyms: Ranunculus californicus var. austromontanus, Ranunculus californicus var. californicus, Ranunculus californicus var. cuneatus, Ranunculus californicus var. gratus, Ranunculus californicus var. rugulosus) -
Cooley's Buttercup: Ranunculus cooleyae -
Alkali Buttercup, Seaside Buttercup, Shore Buttercup: Ranunculus cymbalaria (Synonym: Ranunculus cymbalaria var. saximontanus) -
Eschscholtz's Buttercup: Ranunculus eschscholtzii var. eschscholtzii (Synonyms: Ranunculus eschscholtzii var. typicus, Ranunculus nivalis var. eschsholtzii) -
Snow Buttercup, Suksdorf Buttercup, Suksdorf's Buttercup, Timberline Buttercup: Ranunculus eschscholtzii var. suksdorfii (Synonym: Ranunculus suksdorfii) -
Greater Creeping Spearwort, Yellow Water Buttercup: Ranunculus flabellaris (Synonym: Ranunculus delphinifolius) -
Creeping Buttercup, Creeping Speerwort, Lesser Spearwort, Small Creeping Buttercup: Ranunculus flammula (Synonyms: Ranunculus flammula var. angustifolilus, Ranunculus flammula var. filiformis, Ranunculus flammula var. flammula, Ranunculus flammula var. ovalis, Ranunculus flammula var. reptans, Ranunculus flammula var. samolifolius, Ranunculus reptans, Ranunculus reptans var. filiformis, Ranunculus reptans var. ovalis) - Note: Washington has split this taxon into 3 varieties: flammula, ovalis and reptans.
Elliptical Buttercup, Sagebrush Buttercup: Ranunculus glaberrimus var. ellipticus (Synonyms: Ranunculus ellipticus, Ranunculus glaberrimus var. buddii) - Found west of the Cascades only on the Siskiyou Crest and in the eastern Olympic Mountains.
Sagebrush Buttercup, Wax Buttercup: Ranunculus glaberrimus var. glaberrimus (Synonym: Ranunculus glaberrimus var. glaberrimus) -
Gorman's Buttercup: Ranunculus gormanii -
Arctic Buttercup: Ranunculus grayi (Synonyms: Ranunculus gelidus var. grayi, Ranunculus verecundus) -
Downy Buttercup: Ranunculus hebecarpus -
Lobb's Aquatic Buttercup, Lobb's Buttercup, Lobb's Water Buttercup: Ranunculus lobbii (Synonym: Ranunculus aquatilis var. lobbii) -
Macoun's Buttercup: Ranunculus macounii (Synonyms: Ranunculus macounii var. macounii, Ranunculus macounii var. oreganus) -
Spiny-fruit Buttercup, Spiny-fruited Buttercup: Ranunculus muricatus -
Western Buttercup: Ranunculus 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) -
Bird's Foot Buttercup, Straightbeak Buttercup, Straight-beak 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, Straight-beak Buttercup: Ranunculus orthorhynchus var. platyphyllus (Synonym: Ranunculus orthorhynchus ssp. platyphyllus) - Found west of the Cascades at a few locations in southwestern Oregon and western Washington.
Small-flower Buttercup, Small-flowered Buttercup: Ranunculus parviflorus -
Pennsylvania Buttercup: Ranunculus pensylvanicus -
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) - Flowers shiny yellow, quarter-sized, and with 5 or more petals. Leavesdark green, coarsely haired, and compound with deep lobes. Plants spread by runners across the ground. Plants to 1 foot tall.
Hairy Buttercup: Ranunculus sardous (Synonym: Ranunculus parvulus) -
Blister Buttercup, Celeryleaved Buttercup, Celery-leaved Buttercup, Cursed Buttercup, Division Blister Buttercup: Ranunculus sceleratus var. multifidus (Synonym: Ranunculus sceleratus ssp. multifidus) -
Blister Buttercup, Celery-leaved Buttercup: Ranunculus sceleratus var. sceleratus (Synonym: 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. uncinatus) - Flowers small (less than dime-sized) and shiny yellow. flowers are found directly above the 3 lobed leaves. Plants to 2 feet tall.