Identification of a population of Ranunculus achenes extracted from Middle Pleistocene sediments exposed at Belhus Park, Essex, UK

Abstract

ABSTRACT A plant macrofossil assemblage extracted from Middle Pleistocene fluvial organic sediments collected from Belhus Park, Aveley, Essex, UK contained a number of tuberculate (verrucose) achenes attributed to the genus Ranunculus, one of which had two short spines preserved on its surface. The identification of these achenes is discussed here. This is worthy of note because Ranunculus tuberculate or spinose fossil achenes can be difficult to determine to species as they can have similar features, some Ranunculus species produce achenes in several morphological forms, and during fossilization delicate structures maybe destroyed (e.g. spines). After careful morphological consideration it is concluded that the fossil achenes from Belhus Park are Ranunculus parviflorus L., indicating that dry grassland or disturbed ground existed in the river catchment. The plant macrofossil assemblages that included the Ranunculus parviflorus achenes were dominated by waterside, damp ground, and aquatic taxa. It is probable that flowing water transported the achenes from further afield before their incorporation into the fluvial sediments. The identification of these fossils illustrates the importance of considering the morphological characteristics of the achene only and not to make a determination on the nature of the predominant palaeoenvironmental signal from an assemblage.