Morphometric analyses of mixed Dactylorhiza colonies (Orchidaceae) on industrial waste sites in England

Abstract

Morphometric data were collected from Dactylorhiza growing on two types of industrial waste (pulverized fuel ash or PFA, and Leblanc process waste) during the summer of 1997. Three species grew on PFA (D. fuchsii, D. incarnata, D. praetermissa). The same species plus D. purpurella grew on the Leblanc site, although on both substrates the majority of plants failed to correspond precisely with published descriptions, introducing an element of subjectivity into the field identifications. Principal Components Analysis and Detrended Correspondence Analysis ordinations confirmed that textbook species descriptions corresponded to extremes of multivariate space. Cluster Analysis failed to produce a useful resolution of the data. Discriminant Functions Analysis initially gave the misleading result that any plant with spotted leaves was D. fuchsii, but produced useful results after leaf spotting was removed from the analysis. On PFA sites hybrids appeared to be mainly D. praetermissa×D. fuchsii (=D. grandis)or D. praetermissa×D. incarnata (=D. wintoni). The identity of hybrids on the Leblanc site was unclear, perhaps reflecting the greater age of this site which may have allowed extensive introgression.