Ranunculus ficaria is a perennial herb, spring ephemeral, extensively, aggressively colonial, forming dense, low mats from tuberous roots, stems succulent, reclining 10-30 cm long, leaves die off as canopy closes in late May, dormant by late May-early June; sap toxic.
Leaves alternate, bluntly heart-shaped, shiny, basal; often with small bulbs in axils.
Flowers yellow, buttercup-like, 2 cm wide, petals 8-12, March-April.
Fruits dry achenes.
Wetland status: UPL but usually in moist soil of flood plains (Gargiullo, personal observation).
Frequency in NYC: Occasional. Very extensive local colonies.
Habitat: Mostly found growing in moist soil. In NYC found in soil with pH 6.5-7.6 (Gargiullo unpublished data). Part shade, woods, edges, stream banks, flood plains.
Notes: Seeds and plants eaten by many birds and mammals (Martin et al. 1951). Erythronium americanum and Claytonia virginiana have been observed to sometimes come up sparingly through colonies of lesser celandine (Gargiullo, personal observation). Contains the toxic oil protoanemonin (Kingsbury 1964).