Centaurea horrida is endemic to Sardinia, where it has a very restricted extent of occurrence and area of occupancy of 172 km² and 42 km² respectively with a total of four locations. It grows in coastal habitats on rocks and sea cliffs which have been under much pressure from human activities such as construction works and tourist use. Further threats are overgrazing as well as the abandonment of pasture activities which lead to succession and high competition. Some of the populations are protected. Therefore, it has been assessed as Endangered.

Centaurea horrida is endemic to Sardinia. It grows between 0-240 m above sea level (Pignatti et al. 2001). Its distribution is limited to sea-cliffs in islands and peninsulas where it forms patches of isolated populations, both in primary and secondary dwarf communities (Biondi et al. 2001).
The extent of occurrence and area of occupancy are therefore very restricted and are 172 km² and 42 km² respectively with a total of four locations (Pisanu and Filigheddu in: Rossi et al. 2008).

The species is present in five subpopulations, defined as geographically distinct groups within the population:

• Isola Asinara, Provincia di Sassari, Comune di Porto Torres;
• Isola Piana, Provincia di Sassari, Comune di Porto Torres;
• Penisola di Stintino, Provincia di Sassari, Comune di Stintino;
• Penisola di Capo Caccia: Provincia di Sassari, Comune di Alghero;
• Isola Tavolara, Provincia di Olbia-Tempio, Comune di Olbia (Pisanu and Filigheddu in: Rossi et al. 2008).

The five sites differ in terms of geography, substrata and land use (Pisanu and Filigheddu in: Rossi et al. 2008; Pisanu et al. 2009).
The population trend seems to be stable, but a strong decrease of the habitat, about 20% in the last 50 years has been recorded, due to change of management regime and infrastructure development (Pisanu and Filigheddu in: Rossi et al. 2008).

It is an heliophylic and xerophytic plant who grows in coastal areas and on different substrates on calcareous, dolomitic, granitic or metamorphic rocks (Pignatti et al. 2001). Centaurea horrida can be found in the following Habitats Directive listed habitats (Commission of the European Communities 2009):

• 1240 Vegetated sea cliffs of the Mediterranean coasts with endemic Limonium spp.
• 5320 Low formations of Euphorbia close to cliffs

The coastal habitat occupied by C. horrida has decreased from 36.67 km in 1956 to 29.84 km in 2006. Therefore, the extent of habitat has undergone a continuous decline of 18.62% in 50 years (Pisanu et al. 2009).

The main threat to the species is habitat loss either due to the change of management regime such as abandonment of pasture activities that lead to vegetation succession and overgrowth with Juniperus phoenicea L. ssp. turbinate (Farris et al. 2009) or due to infrastructure development, especially for tourism. The latter has led to a documented habitat loss of 27.2% in 50 years, measured as a decrease in coastal perimeter, after construction and tourist use of the cliffs (Pisanu and Filigheddu in: Rossi et al. 2008, Pisanu et al. 2009). Furthermore, the grazing by introduced or native ungulates impacts on this plant (Pisanu and Filigheddu in: Rossi et al. 2008, Pisanu et al. 2009). On Tavolara Island, C. horrida is hybridising with the congeneric Centaurea filiformis Viv. (Pisanu et al. 2009, Pisanu et al. 2010).

Moreover, the plant has a very limited dispersal ability: more than 60% of the seedlings grow very close to the mother plant (Pisanu and Filigheddu in: Rossi et al. 2008, Pisanu et al. 2009) and genetic analysis revealed a very low genetic flow among populations (Mameli et al. 2008).

This plant is listed as priority species on Annex II of the Habitats Directive and under Appendix I of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention).

Centaurea horrida was listed as Vulnerable on the last national red lists (Pignatti et al. 2001, Conti et al. 1997).

Three subpopulations are within protected areas (the Regional Park of Porto Conte, established in 1999; the National Park of Asinara, established in 1997; the Protected Marine Area of Tavolara-Punta Coda Cavallo, established in 1997). Two subpopulations have no effective protection, even though they are located in two “Natura 2000” sites (ITB010043: coasts and islets of northwest Sardinia; ITB010082: Piana Islet). There are 150 seeds stored in the Seed Bank of the University of Cagliari (BG-SAR).