Spermogonia: in small clusters, amphigenous, honey-coloured or orange-red [Wilson & Henderson 1966].
Aecia: usually epiphyllous, sometimes on yellowish spots, often confluent in concentric rings around the spermogonia, cinnamon-brown, pulverulent. Aeciospores 22-30 x 16-28 µm, subgobose to broadly ellipsoidal, brown, the wall echinulate, 2-2.5 µm thick, with three equatorial pores [Wilson & Henderson 1966].
Uredinia: usually hypophyllous, minute, pulverulent, brown. Urediniospores 26-28 x 23-25 µm (only a few measured), morphologically very similar to the aeciospores.
Telia: mostly hypophyllous, small, scattered or confluent in small groups, pulverulent, blackish brown. Teliospores (27-) 30-34 x 17-21 µm [24-50 x 16-27 µm fide Wilson & Henderson 1966], ellipsoidal to cylindric-ellipsoidal, rarely obovoid or angular, chestnut brown, hardly constricted at the ± median septum, the wall faintly verruculose, pore of the upper cell almost apical, of the lower cell towards the septum. Pedicels hyaline, slender, to 40 µm long, deciduous, sometimes eccentrically attached.
Not formally assessed, but the species is common and widespread.
On leaves and stemps of Centaurea nigra and C. scabiosa.
The species is traditionally considered to have a broad host range, but indications are that it is an aggregate and similar rusts on other genera of Asteraceae are not conspecific. In GBI, these include P. bardanae (on Arctium), P. carduorum (on Carduus), P. punctiformis (on Cirsium arvense), P. cirsii-eriophori (on Cirsium eriophorum), P. laschii (on Cirsium palustre and C. heterophyllum), P. cnici (on Cirsium vulgare), and P. divergens (on Carlina).
The species is usually referred to as P. centaureae in Europe and it may be that populations on Centaurea calcitrapa are not conspecific with those on C. nigra and C. speciosa, but more research is needed.
Throughout Britain and Ireland.