I've been taking a closer look at the Red Campion Silene dioica on my route to work, ever since I heard about Campion Anther Smut Microbotryum violaceum sensu lato (from @fungifrolics). Finally found some! On Sussex Wildlife Trust's Woods Mill nature reserve, near the willow tunnel.
What mycological madness is this, to try and wrap my head around?! This is a fungus which, having infected a host plant, proceeds to take over the plant's sexual parts for its own reproductive purposes. In the place of anthers, which would have borne pollen, the fungus causes the plant to produce a mass of dark brown spores.
There is also a very accessible introduction to the Microbotryum violaeum species complex on A. J. Silverside's website, here. And it seems that modern molecular studies have not yet completely succeeded in resolving the complex into a group of satisfactorily delimited species (Vánky, 2004).
I had read that the spores of Microbotryum are ornamented with a reticulate ('net-like') mesh. This prompted me to spend a few hours playing with the microscope.
Here are a couple of spores from my Woods Mill collection. Both images were taken at 1000x magnification under oil immersion & manually focus-stacked using Helicon Focus.
|Figures 3-4 from Denchev et al (2009). Spores of Microbotryum lychnidis-dioicae (Liro) G. Deml & Oberw. on Silene latifolia in SEM. Bars 3 = 1 μm, 4 = 2 μm. Image © Denchev et al 2009.|
Having been thoroughly distracted by this fungus's biology and rather attractive spores, all that remains is to put a species name to it. Spooner & Legon (2006), in their list of species in the Microbotryum violaceum complex which can be recognised in Britain, have M. lychnidis-dioicae occurring in anthers of Silene dioica. Whereas Vánky (2004), advocates using the name M. violaceum sensu lato, pending further taxonomic work. So there we go. Take your pick.
There are a whole bunch of different Microbotryum species, parasitising different plants. I think one of the most modern comprehensive treatments must by Vánky (1998) but there is also a nice list – with pictures! – in the recent 'Smut and Allied Fungi of Wales' (Woods et al, 2018). Want to find them all now!
Denchev, C. M., Giraud, T. & Hood, M. E. (2009). Three new species of anthericolous smut fungi on Caryophyllaceae. Mycologia Balcanica. 6: 79-84. URL: http://max2.ese.u-psud.fr/publications/Denchev_2009.pdf
Schäfer, A., Kemler, M., Bauer, R. & Begerow, D. (2010). The illustrated life cycle of Microbotryum on the host plant Silene latifolia. Botany. 88. 875-885. 10.1139/B10-061. URL: https://www.researchgate.net/publication/235119641_The_illustrated_life_cycle_of_Microbotryum_on_the_host_plant_Silene_latifolia
Silverside, A.J. Microbotryum violaceum. URL: http://www.bioref.lastdragon.org/Pucciniomycotina/Microbotryum_violaceum.html (accessed June 2019)
Spooner, B.M. & Legon, N.W. (2006). Additions and amendments to the list of British smut fungi. Mycologist. 20(3). pp. 90-96. URL: https://www.sciencedirect.com/science/article/pii/S0269915X06000322
Vánky, K, (1998), The genus Microbotryum (smut fungi). Mycotaxon 67: 33-60.
Vánky, K., (2004), Anther smuts of Caryophyllaceae. Taxonomy, nomenclature, problems in species delimitation. Mycologia Balcanica 1: 189–191. URL: https://zenodo.org/record/2546766#.XOOzcdh7m70
Woods, R.G., Chater, A.O., Smith, P.A., Stringer, R.N. & Evans, D.A. (2018). Smut and Allied Fungi of Wales: A Guide, Red Data List and Census Catalogue. Aberystwyth. URL: https://eprints.soton.ac.uk/425372/1/smut_RDL.pdf
For the record
Location: Woods Mill, West Sussex
Grid ref: TQ217137