SPEER, WILLIAM D.1*, ELIZABETH SHEFFIELD2, and PAUL G. WOLF1. 1Department of Biology, Utah State University, Logan, UT 84322; 2School of Biological Sciences, University of Manchester, Manchester M13 9PL, UK. - Relationships among Northern Hemisphere Pteridium: Some new perspectives.
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