A very common rust

I joined Rachel Bicker and the Gatwick Greenspace gang at Gatwick Wildlife Day yesterday – in the grounds of the Gatwick Aviation Museum. 

Conditions were fairly dry, so I had drawn a blank in my hunt for fungi until the orange-yellow speckling on the leaves of this Musk Mallow Malva moschata caught my eye. Another rust fungus!

Here it is under the stereomicroscope.

Ellis & Ellis's Microfungi on Land Plants has provided a promising candidate for the identity of this rust: Puccinia malvacearum. Malcolm Storey has some images of this species on bioimages.org.uk which look like a good match. 

Here's what I'm seeing under the microscope.

Teliospores 100x magnification. Mounted in water.

Teliospore 44x magnification. Mounted in water.

This matches the description of Puccinia malvacearum in The British Rust Fungi (1913) so I think I can claim an identification on this. Ellis & Ellis describe it as "very common".

Interestingly, W.B. Grove had this to say about Puccinia malvacearum, back in 1913:

It had first appeared in Europe less than 50 years before and W.B. Grove commented that "the rapidity of its distribution has few or no parallels among plant diseases."

I wonder what changes in distribution we can expect to see in the 'rare' Puccinia commutata which I found the other day...

For the record
Date: 23/06/2018
Location: Gatwick Aviation Museum, Charlwood, Surrey (modern administrative & vice county)
Grid reference: TQ250409

Record entered into FRDBI 07/09/2018