Plants and Animals
Ranunculus rhomboideus Prairie buttercup
Small perennial forb (20 cm) of open oak forests and rocky outcrops; basal leaves forming a rosette with hairy, undivided blades; upright stems with smaller deeply lobed leaves; flowers yellow with 5 petals, longer than the sepals.
Status and Rank
US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G5 - Secure
State Rank: S2 - Imperiled
|County||Number of Occurrences||Year Last Observed|
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
In southern Michigan, prairie buttercup is known from sandy barrens and prairie remnants on steep hillsides near lakes and rivers. In the Upper Peninsula, it is found on rocky, south-facing ridges and glades.
Natural Community Types
- Hillside prairie
- Northern bald
- Oak barrens
- Oak openings
- Oak-pine barrens
- Volcanic bedrock glade
- Volcanic cliff
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
In southern Lower Michigan, associates may include black oak, white oak, little bluestem, ground juniper, red cedar, flowering spurge, Pennsylvania sedge, bush-clover, tick-trefoil, Ohio spiderwort, New Jersey tea, rockrose, and bracken fern. On Isle Royale, it may be found with more northern species such as northern white cedar, bunchberry, bluejoint, violet, ticklegrass, yarrow, bearberry, marsh bellflower, pale Indian paintbrush, hair grass, spike-rush, butterwort, ninebark, silverweed, dwarf Canadian primrose, and wild rose.
This species requires open habitats. In southern Michigan, it would benefit from maintenance of the prairie and savanna community through activities like brush removal and prescribed burns. Due to its tendency to occur on steep hillsides and rocky openings, trampling and damage from erosion are also management concerns.
Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.
Survey Period: From fourth week of April to fourth week of May
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- Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region, 4th ed. Indiana Academy of Science, Indianapolis. 921pp.
- Voss, E. G. 1985. Michigan Flora. Part II. Dicots (Saururaceae-Cornaceae). Bulletin of the Cranbrook Institute of Science and University of Michigan Herbarium. 724pp.