Ranunculaceae (Buttercup Family) Synonym(s): Littleleaf Buttercup, Kidney-leaf Buttercup, Early Wood Buttercup Base Flower Color: YellowReproductive Phenology: Mar, Apr, May, JunNotes: Mostly smooth stem. For more information about this plant, Click Here. Similar Species: Rock Buttercup (Ranunculus micranthus Nutt.)