Pteridaceae cytogenetics enzyme electrophoresis ferns morphometrics plastid and nuclear phylogeny spores. wrightiana represent three morphologically distinguishable polyploids that have arisen through repeated hybridization events involving the divergent sexual taxa P. Weaving together data from a diversity of taxonomic approaches, we show that plants identified as P.
These tetraploid hybrids originated independently in two regions of parental sympatry (southern Arizona and west Texas) and are here assigned to P. This was the way in which Rosamond and Lydgate slid gracefully into ease. Literary analysis for the phrase Once More unto the Breach with meaning, origin, usage explained as well as the source text. wrightiana are shown here to be hybrids between the fertile allotetraploid and the tetraploid P. In context, the bolded and underlined phrase had the election is best. In Reply to: Once more unto the brink posted by ITR on October 19, 2007. In addition, occasional sterile tetraploid plants assigned to P. Posted by Gary Martin on October 19, 2007. Relatively common across Arizona and New Mexico, they are here assigned to P. wrightiana, were found to be backcross hybrids between this fertile tetraploid and diploid P. And this one is from the even more famous Once more unto the breach speech. Sterile triploids commonly identified as P. Terry has confirmed that this book was his source for the phrase. wrightiana, is a fertile allotetraploid that arose through hybridization between two divergent diploid species, P. Plants traditionally assigned to this taxon represent three distinct polyploids. The meaning of INTO THE BREACH is used with step/leap/jump (etc.) to indicate providing help that is badly needed, such as by doing a job when there is no one else. Previously published evidence suggested that this "taxon" may represent a polyploid complex rather than a single discrete species, a hypothesis tested here using a multifaceted analytical approach.ĭata derived from cytogenetics, spore analyses, leaf morphometrics, enzyme electrophoresis, and phylogenetic analyses of plastid and nuclear DNA sequences are used to elucidate the origin, relationships, and taxonomic circumscription of P. The taxonomic status of Wright's cliff brake fern, Pellaea wrightiana, has been in dispute ever since it was first described by Hooker in 1858.
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