There are eighteen species of Ranunculus in Michigan, so narrowing them down can be a challenge. Most of the species have very short petals so two-thirds can be eliminated immediately when trying to identify this plant. Of the remaining six species only only three occur in Mid-Michigan. Of the remaining three, R. fascicularis only occurs in upland sites. That leaves R. acris and R. hispidus as possible species. Both species of plants favor wetlands so habitat alone cannot be used to identify them.
To complete the identification, you have to look at the leaves. Tall Buttercup (Ranunculus acris) has simple, deeply lobed leaves. Swamp or Bristly Buttercup (Ranunculus hispidus) also has deeply lobed leaves, but on R. hispidus the leaves are compound with the terminal lobe (leaflet) having a definite stalk. Because these plants have compound leaves that gives us Swamp Buttercup as our identification.
The Swamp Buttercup blooms from April into July. Its flowers are approximately 1/2 to 1 inch across. The petals are widest their midpoint and are up to twice as long as the sepals.
|Swamp Buttercup (Ranunculus hispidus) - note the compound leaves|
|Swamp Buttercup (Ranunculus hispidus)|