The therophytic flora of Sardinia has been split into four main groups, basing on the ecologic requirements of species. The following groups have been recognized: flora of dry entisoils, flora of periodically swampy or submerged entisoils, flora of coastal sites, flora of fields, road edges and human settlements. Either, most frequent or exclusive species were ascribed to each group. A species was considered “exclusive” when its relative frequency outside a given group was estimated ≤10%. Differences have been highlighted within the groups, dealing with chorology, growth form, flowering time, colour of flowers, pollination and seed dispersal strategies.