Figure 2.

Absolute amounts of alkanes (black bars) and alkenes (grey bars) in orchid groups with contrasting pollinators. Orchids pollinated primarily by male bees (Ophrys sphegodes, Serapias lingua, S. cordigera, Anacamptis papilionacea) produce significantly more alkenes (ANOVA, F_2,14 = 5.89, P = 0.01; see text for posthoc statistics) than the other groups of species. The amounts of alkanes were not significantly different among the pollinator-defined groups.