Wikipedia
Phragmidium
'Phragmidium ' is a genus of rust fungus that typically infects plant species in the Rosaceae. It is characterised by having stalked teliospores borne on telia each having a row of four or more cells. All species have a caeoma which is a diffuse aecidium lacking a peridium.
There are a number of species of 'Phragmidium most of which are restricted to one or a few host species. Examples include:
- P. acuminatum on Rubus saxatile
- P. bulbosum on Rubus fruticosus and Rubeus caesius
- P. sterilis on Potentilla sterilis
- P. potentillae on Potentilla anglica
- P. rubi-idea on Raspberry
- P. tuberculatum on some Rose cultivars
- P. violaceum on cultivated Blackberry and Loganberry
Possible the most commonly encountered is P. mucronatum found on most species of wild roses including Rosa canina and '' Rosa arvensis