Studi sulla cariologia delle asclepiadaceae

Summary

The author examines the sole station so far found in Sardinia of Satureja Thymbra Willd., a species common only in the Eastern Mediterranean, with a range including at the western extreme the islands of the Ionian sea and the vicinity of Derna in Cyrenaica, except for the isolated station described on Mount San Michele near Cagliari.

In this station, few woody and numerous herbaceous species make up the association with S. Tymbra, which in the Eastern Mediterranean forms part of the phrygana, according to some Authors, or of the batha according to others, this latter being a gradation lower ecologico-climatically than the garigue and the phrygana. Phrygana and batha populations do not exist in the Western Mediterranean.

The San Michele station might be conveniently classified as a tomillares owing to the presence of certain Labiatae species, but because the more characteristic species of this association are lacking as compared with the Iberian Peninsula, the Author considers this population to be of the steppe type with Labiatae in which many of the steppe Graminaceae are present, though again not the most characteristic.

The Author then examines the genetic and phylogenetic aspects of the species, which he considers to be linked with the geological events of the period corresponding to the existence of the Tyrrhenian continent, between the upper Miocene and the lower Pliocene (Pontian).