Phragmidium

Phragmidium is a genus of rust fungus that typically infects plant species in the family 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: Phragmidium acuminatum on Rubus saxatile Phragmidium bulbosum on Rubus fruticosus and Rubeus caesius Phragmidium mucronatum Phragmidium sterilis on Potentilla sterilis Phragmidium potentillae on Potentilla anglica Phragmidium rosae-pimpinellifoliae Phragmidium rubi-idaei on raspberry Phragmidium tuberculatum on some rose cultivars Phragmidium violaceum on cultivated blackberry and loganberry