Thecaphora trailii Cooke, 1883
on Cirsium, Saussurea
Cirsium dissectum, England, Oxon, VC23 © Malcolm Storey, Bioimages
the spore balls easily disintegrate
one or more cavities in the disfigured, never opening flower head are filled with a brown, granular-powdery mass of spore balls. Sometimes similar sori are formed as pustules on the peduncle below the flower head. The easily desintegrating spore balls consist of c. 2-5 spores.
Asteraceae, narrowly oligophagous
Experimentally also C. oleraceum, palustre, and vulgare could be infected.
Ainsworth & Sampson (1950a), Buhr (1964b), Klenke & Scholler (2015a), Tomasi (2014a), Vánky (1994a).