Ranunculus hederaceus

History of Spread

Ranunculus hederaceus (Ivy-Leaved Buttercup) is now found in western Europe, from Scandinavia to Spain, and in coastal regions of North America, from Newfoundland to NC (Fernald 1950; Gleason and Cronquist 1991; Swedish Natural History Museum 2001). Its typical habitat is 'shallow pools, rills, and wet sandy depressions' (Fernald 1950), and its North American distribution is disjunct, with isolated populations in Newfoundland, and then more continuous, but still scattered occurrences, from the Delaware River valley in PA, along Chesapeake tributaries in MD and VA, to northernmost NC, and 2 coastal counties in SC (Swedish Natural History Museum 2001; Natural Resources Conservation Service 2001). This distribution could be explained by regarding it as a glacial relict, with Newfoundland populations having dispersed from a coastal refugium, now submerged, and other North American populations occurring only south of the glaciation (Fernald 1940). Alternatively, this plant may have been an introduction from Europe (Gray 1867; Robinson and Fernald 1908; Cook 1985). It could have been introduced with dry ballast, but its occurrence near coastal springs suggests that ship's water barrels, and buckets are a possible mechanism.

Cook (1985) reports the first North American specimen of this plant as being collected in 1821, but does not give a location. Gray (1867) gives the first published record which we found, from 'freshwater marshes' in Norfolk VA. By 1908, it was known to occur in Newfoundland, as well as in southeast Virginia (Robinson and Fernald 1908).

Although R. hederaceus is a possible introduction (cryptogenic) in North America, a Web search indicates that it is on state 'threatened' lists in NC, VA, and MD and is listed as 'extirpated' in PA. It is also on local lists of rare plants in Europe, and is extinct over much of its former range there (Swedish Natural History Museum 2001). This plant's habitat of springs and streams in coastal wetlands proably makes it very vulnerable to disturbance.

Chesapeake Bay records include Gray's (1867) record from Norfolk, and Fernald's (1940) description of it occurring in mats on 'springy ground' beside Back Bay, an arm of Currituck Sound in Virginia Beach. In addition, there are several National Herbarium specimens:

Potomac River- 1934, Stratford, Westmoreland County VA. 'Sandy delta at mouth of run at Stratford Cliffs'. 1949- Charles County, MD. 'Spring seepage, sandy muck on the northeast side of Wise Marsh, at the head of Cuckold Creek (U.S. National Herbarium collections).

Patuxent River- 1900, Upper Marlboro, Prince George County VA, 'swamp south of confuence of Western Branch with Patuxent River, in spring deltas running over marl'. (U.S. National Herbarium collections). 1907- Mt. Calvert, Prince Georges County (U.S. National Herbarium collections).

References- Cook 1985; Gray 1867; Fernald 1940; Robinson and Fernald 1908; Swedish Natural History Museum 2001; Natural Resources Conservation Service 2001; U.S. National Herbarium collections

Invasion Comments