The systematic relationships among many Pteridium (bracken) taxa are still poorly understood. We sequenced several genes in an attempt to infer relationships between the Northern Hemisphere taxa. Samples were obtained from bracken in Britain, Europe, Japan, North America, and Hawaii representing the Pteridium aquilinum varieties aquilinum, latiusculum, pseudocaudatum, pubescens, and decompositum. Samples of the southern hemisphere Pteridium esculentum were also included as an outgroup in the study. Of particular interest were the results obtained from the chloroplast rps4 gene sequences. In general, British and European var. aquilinum were united by a 5bp insertion that was not present in any of the non-aquilinum material. A strong similarity was observed also between rps4 sequences from Hawaiian decompositum and western North American pubescens. Phylogenetic analyses of rps4 sequences suggest two main clades. The first was represented by British and European aquilinum. The second was predominately latiusculum, but included the North American and Hawaiian taxa. In most analyses, the Eurasian latiusculum tended to form a single group. In all analyses conducted, decompositum and pubescens formed a single group. This study provides important information needed for a global study of bracken systematics.

Key words: Pteridium aquilinum , bracken, chloroplast genes, phylogenetics