Article

The authors examine the results obtained as regards the floristic heritage on the Etnean botanic garden after more than 20 years. Up unti I 1995, 464 species had been counted in the garden. Of these, 136 belong to the sponta-neous flora, while 328 species were introduced and come from various parts of the MI. Etna territory. Of the latter group, some species did not manage to survive after introduction, while about 14% (71 species) became spontaneous. Most of these belong to the basaI Mediterranean belt while a small number belong to the mountain-Mediterranean belI. The results show that after some years of activity, the biodiversity in the garden has increased by about 200% thanks to the ecological adaptability of some of the introduced species. This process was helped by the work required for the running ofthe garden itself(potting, irrigation, the providing of shade and so on). Among the introduced species, the higher adaptability is shown by the hemicryptophyte and therophyte Iife forrns which are the most represented (60%) types. As regards the chorology there is a predominance of the Mediterranean s.I. species (about 43%), which have, therefore, a wide ecological valency. Such ecological valency is al so shown by the species which spontaneously spread.