Monday, October 18, 2010

More Smut - Sex-change in Campion Flowers

A while back I posted some pictures of the smut fungus Microbotryum violaceum infecting the anthers of white campion .The flower above is a pink campion - probably a hybrid between white campion Silene latifolia and red campion Silene dioica - whose stamens are also full of the brown fungal spores. Both red and white campions exist as separate male and female plants. This fungus fills the anthers of male plants with its spores which are carried from flower to flower by pollinating insects, but it also brings about a change in the sex of female flowers, so that the female structures are suppressed and appendages called staminodes develop into stamen-like structures that produce the fungal spores and attract insects that are fooled into thinking they are collecting pollen grains. So, when the whole local population has been infected with the sex-changing smut fungus, how do you separate the genuine males from the gender switching females? 

 You need to look closely, under the microscope. If the 'stamens' are simply full of fingal spores, like those above, then you are looking a gender-switching female, but.....

......  if there are a few large pollen grains amongst the tiny fungal spores, then you are looking at a genuine male plant that was infected after the pollen grains began to develop.