Abstract
Following the first two contributions for a new, updated, and revised vascular flora of Sardinia, new data about the distribution of 30 taxa growing in the island are here presented. Taxa are both native and alien, and are characterized by their very low frequency, phytogeographical significance, endemicity, conservation status, invasiveness or novelty to Sardinia and Italy. The results derive from floristic research carried out throughout Sardinia and various neighbouring islands and islets. The first reports of Bulbine frutescens, Coleus barbatus, Dasylirion serratifolium, Euphorbia ingens, and E. milii are here recorded for the first time in Italy (casual alien). Additionally, Ageratum conyzoides, Cyperus papyrus, Erysimum odoratum, Galinsoga quadriradiata, and Narcissus trumpet daffodil group (casual alien taxa) are documented here for the first time in Sardinia. Moreover, the confirmations for Sardinian flora of Carex acutiformis, Catananche lutea, and Suaeda splendens are here provided after 40 years without new reports. New distributional data for 12 taxa, most of which known for their rarity, are gathered. Notably, Callitriche lusitanica was previously reported only for a few sites. Concerning other taxa, a clarification of their distribution range on the island is documented, as for the rare Ceratophyllum submersum subsp. submersum, Limoniastrum monopetalum, and Malva stenopetala subsp. plazzae, which have recently faced contraction after human activities on their previously known locations. New data are also provided for some rare endemics, including Romulea revelierei, Silene velutina, and Stachys salisii. New findings are also reported for Cachrys libanotis, Chamaerops humilis, Damasonium bourgaei, Linum tenuifolium, Monotropa hypopitys (rare to scattered native). In addition, updated information on the distribution of Arctotheca calendula, Delairea odorata, Gazania ×splendens, Kalanchoe ×houghtonii, and Tropaeolum majus (invasive alien taxa) is here reported. Finally, new data about some of the taxa recorded in the first two contributions are added below.