GENE VARIATION AND GENE FLOW IN ORCHIS-MORIO (ORCHIDACEAE) FROM ITALY

Data are presented on genetic variation at 27 enzyme loci of the Green-Winged orchid, Orchis morio, in 18 population samples from Italy. The existence in Italy of two subspecies, i.e. subspp. morio and picta, is not supported by allozyme data. No genetic heterogeneity was found between morio-like and picta-like samples and specimens. Moreover, morphological transition between the two forms was observed in different Italian populations. The parameters of genetic variability estimated for O. morio populations are consistent with those found among monocotyledon plants, and among those outcrossing, animal-pollinated and with wind-dispersed seeds. Genetic diversity of Italian O. morio is mostly within populations. Correspondingly, low values of interpopulational genetic distance were found. This appears to be due to high levels of gene flow, which were estimated with different methods. The lack of O. longicornu from Italian samples, as well as of any hybrid with O. morio (F1, backcrossed or recombinant individuals) is demonstrated on the basis of genetic data. It is concluded that recurrent reports of O. longicornu from Italy are due to confusion with O. morio or with other Orchis species.