Dispersed Fern Sporangia from the British Tertiary

Abstract

Dispersed fern sporangia have been recovered from the Bembridge Marls of the Isle of Wight and from Bracklesham deposits in a borehole West of Poole, Dorset. These fern sporangia confirm the presence of the family Polypodiaceae s.1. in the British Tertiary flora. Previously records of this family have been based solely on vegetative material, usually fragmentary, for which taxonomic assignment is inevitably insecure. The sporangia, containing spores and with adherent paraphyses, are shown to be most comparable with the Recent genus Acrostichum L. and are described as Acrostichum anglicumsp. nov. The distribution and occurrence of these sporangia suggests the extensive development of Acrostichum in the lacustrine environments of Bembridge times.