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1 December 2008 Morphological Discrimination of Platanthera aquilonis, P. huronensis, and P. dilatata (Orchidaceae) Herbarium Specimens
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Several nomenclatural changes have taken place in Platanthera within the past decade, including the recircumscription of species and newly described segregate taxa. Collections in herbaria should be updated to reflect these changes, however Platanthera herbarium specimens are difficult to identify because diagnostic qualitative and quantitative characters present in the field are not always available in dried material. Such a problem is found in P. hyperborea s. lat. from continental North America, which is now known to comprise the diploid P. aquilonis and the putative allotetraploid P. huronensis. Platanthera aquilonis and P. dilatata are commonly regarded as progenitors of P. huronensis. Platanthera hyperborea s. str. is not known to occur in continental North America. I undertook a study to determine if herbarium specimens of P. hyperborea s. lat. and the closely related P. dilatata representing British Columbia populations could be annotated to reflect the current taxonomic treatment. I placed P. hyperborea s. lat. and P. dilatata herbarium specimens into groups using keys and descriptions provided in recent treatments. Principal components analysis (PCA) and ANOVAs were used to determine if groups existed in the data set. The univariate statistics supported the presence of three groups in the data set and individuals of known ploidy helped to confirm that phenetic clusters on the PCA scatterplot corresponded to the appropriate species. Using techniques outlined in this paper, Platanthera herbarium specimens can be annotated to reflect current taxonomic treatments.

Christopher J. Sears "Morphological Discrimination of Platanthera aquilonis, P. huronensis, and P. dilatata (Orchidaceae) Herbarium Specimens," Rhodora 110(944), 389-405, (1 December 2008).
Published: 1 December 2008

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