This biannual thistle with a Mediterranean-Turanian distribution is present in all regions of Italy. It grows in disturbed sites, such as arid and sunny slopes and margins of roads and railways, on both calcareous and siliceous substrates, on primitive soils which are rich in skeleton but rich in bases and very dry in the summer, from sea level to the lower montane zone. The species is sporadic on the edge of the Sardinian temporary ponds, in contact with ruderal vegetation. The genus name was already in use among the Romans; from it derives the expression 'carding wool', an operation in which, until recently, the heads of several thorny Asteraceae and Dipsacus were used; the species name comes from the Greek 'pyknos' (thick), referring to the flower heads which are crowded at the apex of stems. Flowering period: April to June.

Italian name(s): Baxaprei (Liguria, Cogorno), Bugnagun (Emilia-Romagna, Reggio), Bunagun (Emilia-Romagna, Reggio), Cardo a teste addensate (Italia), Cardo de' campi (Toscana), Cardo picnocefalo (Italia), Cardo saettone (Italia), Cardogna (Campania), Erba spinosa (Liguria, Mignanego), Gard piscia piscia (Sardegna, Alghero), Insaleta d'ezen (Emilia-Romagna, Reggio), Magnazzu (Sicilia), Pancaud (Piemonte), Saittuni (Sicilia), Scarzun (Emilia-Romagna, Reggio), Spinazzi (Liguria, Montaldo).