Figure 4.

Floral scent clustering. Floral odour similarity between samples of Ophrys arachnitiformis (solid, black bar), hybrids (open bar) and O. lupercalis (solid, grey bar) in the orchid hybrid zone. The UPGMA cladogram was based on pairwise Euclidean distance in floral odour (relative proportions of all compounds, in %) between samples. Individuals are grouped together according to taxa (except for one sample, labelled "23Hybr3"), and hybrids cluster together with O. lupercalis (open circle at internal node), whereas samples of O. arachnitiformis cluster separately (solid circle at internal node).