Anther Smut - a sexually transmitted disease of campion flowers

We found red campion flowers on the banks of the river Tyne near Wylam today that were infected with campion anther smut fungus Microbotryum violaceum .

The anthers of this plant were particularly heavily infected and rain had washed the purplish-brown spores of the fungus onto the petals.

When the anther smut infects its host it proliferates in the stamens, producing tens of thousands of these microscopically small, spiny spores that are then carried from flower to flower by pollinating insects, like the drone fly that’s visiting the red campion flower below.

 Hijacking the plant's stamens and pollinators to produce and spread its spores around would be a remarkable adaptation, but this fungus goes one step further in exploiting its host. 

Campion plants are either male or female and only males have the stamens that the fungus needs for development of its spores, but when the fungal spores infect a female campion - which would not normally produce stamens in which the fungal spores proliferate - it induces the female plant to change sex and become male, producing stamens where its spores can multiply.

The smut fungus symptoms are particularly conspicuous in white campion Silene alba, where the petals are stained purple