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Bur Buttercup, Curveseed Butterwort, Hornseed, Hornseed Buttercup: Ceratocephala testiculata (Synonyms: Ceratocephalus orthoceras, Ranunculus testiculatus) - Annual. Flower stems 1-flowered.
Meadow Buttercup, Showy Buttercup, Tall Buttercup: Ranunculus acris (Synonyms: Ranunculus acris, Ranunculus acris ssp. strigulosus, Ranunculus acris var. latisectus, Ranunculus acris var. stevenii, Ranunculus acris var. typicus, Ranunculus acris var. villosus, Ranunculus boreanus) -
Plantain-leaf Buttercup, Plantain-leaved Buttercup: Ranunculus alismifolius var. alismifolius (Synonym: Ranunculus alismaefolius var. alismaefolius) - Leaves simple with entire margins, the leaves elliptic to broadly lanceolate in outline, long and usually over 1 cm wide. Petals generally 9-10 mm long. Plants of most meadows, grasslands to montane slopes.
Leafy Water Buttercup, White Water-buttercup: Ranunculus aquatilis var. aquatilis (Synonyms: Batrachium aquatile, Ranunculus aquatilis, Ranunculus aquatilis var. hispidulus, Ranunculus aquatilis var. typicus, Ranunculus trichophyllus var. hispidulus) -
Water Buttercup, White Water Buttercup: Ranunculus aquatilis var. diffusus (Synonyms: Batrachium circinatum, Batrachium circinatum ssp. subrigidum, Batrachium longirostre, Ranunculus amphibius, Ranunculus aquatilis var. caespitosus, Ranunculus aquatilis var. capillaceus, Ranunculus aquatilis var. longirostris, Ranunculus aquatilis var. subrigidus, Ranunculus aquatilis var. trichophyllus, Ranunculus circinatus, Ranunculus circinatus var. subrigidus, Ranunculus longirostris, Ranunculus subrigidus, Ranunclus trichophyllus, Ranunculus trichophyllus var. trichophyllus, Ranunculus usneoides) - Plants aquatic, often floating in water. Floating leaves finely dissected, divided into numerous narrow segments. Petals 5-10 mm long.
Alkali Buttercup, Seaside Buttercup, Shore Buttercup: Ranunculus cymbalaria (Synonyms: Cyrtorhyncha cymbalaria ssp. alpina, Halerpestes cymbalaria, Halerpestes cymbalaria ssp. saximontana, Ranunculus cymbalaria ssp. saximontanus, Ranunculus cymbalaria var. alpinus, Ranunculus cymbalaria var. saximontana, Ranunculus cymbalaria var. saximontanus, Ranunculus cymbalaria var. typicus) - Leaves simple with rounded teeth along the margins or more or less 3-lobed near the tips. Wet shores.
Yellow Water Buttercup: Ranunculus flabellaris (Synonym: Ranunculus delphinifolius) -
Creeping Buttercup, Greater Creeping Spearwort, Lesser Spearwort, Small Creeping Buttercup: Ranunculus flammula (Synonyms: Ranunculus filiformis, Ranunculus filiformis var. ovalis, Ranunculus flammula var. angustifolius, Ranunculus flammula var. filiformis, Ranunculus flammula var. flammula, Ranunculus flammula var. genuinus, Ranunculus flammula var. intermedia, Ranunculus flammula var. ovalis, Ranunculus flammula var. reptans, Ranunculus flammula var. samolifolius, Ranunculus flammula var. strigulosus, Ranunculus flammula var. unalaschensis, Ranunculus reptans, Ranunculus reptans var. filiformis, Ranunculus reptans var. intermedius, Ranunculus reptans var. ovalis, Ranunculus reptans var. samolifolius, Ranunculus reptans var. strigulosus) - Leaves simple with entire margins, elliptic in outline.. Stems prostrate or spreading, rooting at the nodes. Petals 4-5 mm long. Mudflats of wet shores.
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) - Leaves simple with entire to deeply lobed bases, or tri-lobed at the tips. Yellow petals 8-15 mm long.
Delicate Buttercup, Downy Buttercup: Ranunculus hebecarpus -
Lobb's Buttercup, Lobb's Water Buttercup: Ranunculus lobbii (Synonym: Ranunculus aquatilis var. lobbii) - Plants aquatic, often floating in water. Floating leaves ternately, deeply divided but not with numerous, fan-like divisions. Petals 4-6 mm long.
Macoun's Buttercup: Ranunculus macounii (Synonyms: Ranunculus macounii var. macounii, Ranunculus macounii var. oreganus) -
Spinyfruit Buttercup, Spiny-fruit Buttercup: Ranunculus muricatus - ? Collected at Bingen, WA in 1929.
Western Buttercup: Ranunculus occidentalis (Synonyms: Ranunculus eisenii, Ranunculus howellii, Ranunculus occidentalis var. dissectus, Ranunculus occidentalis var. eisenii, Ranunculus occidentalis var. howellii, Ranunculus occidentalis var. occidentalis, Ranunculus occidentalis var. rattanii, Ranunculus occidentalis var. typicus, 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) -
Pennsylvania Buttercup, Bristly Buttercup: Ranunculus pensylvanicus -
Creeping Buttercup: Ranunculus repens (Synonyms: Ranunculus repens var. degeneratus, Ranunculus repens var. erectus, Ranunculus repens var. glabratus, Ranunculus repens var. linearilobus, Ranunculus repens var. pleniflorus, Ranunculus repens var. repens, Ranunculus repens var. typicus, Ranunculus repens var. villosus) -
Hairy Buttercup: Ranunculus sardous (Synonym: Ranunculus parvulus) -
Blister Buttercup, Celery-leaf Buttercup, Cursed Buttercup, Division Blister Buttercup: Ranunculus sceleratus var. multifidus (Synonyms: Ranunculus sceleratus ssp. multifidus) -
The Dalles Mountain Buttercup, Obscure Buttercup: Ranunculus triternatus (Synonyms: Ranunculus glaberrimus var. reconditus, Ranunculus reconditus) - Leaves triternately dissected into narrow, linear segments. Yellow petals 8-15 mm long.
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) -