The small, slender knotweed Persicaria foliosa is endemic to the Nordic region and has its centre of occurrences around the Baltic Sea. It occurs as a very rare species on inundated river shores in the eastern parts of southern Norway.
I photographed and documented it for my ongoing Aquatic Macrophyte project, and have kept a culture over the summer to have a look at its seeds. However, Nature being what it is - full of surprises - so instead of seed set the knotweed got flowers infected with the smut fungus Sphacelotheca hydropiperis (Schumacher) de Bary 1884. To the best of my knowledge this parasitic fungus never has been reported with P. foliosa as a host. There is a first time for everything, apparently.
I documented the smut by microphotographs of its spores, plus getting an overview of the infection with my workhorse Laowa 25mm f/2.8 Ultra-Macro lens on one of my Z7 bodies. The Laowa 25 is surprisingly sharp set wide open, and stacking 100 frames in Zerene did the rest. Below is a 100% crop of the frame. The scale bar is 1mm overall with 1/100mm steps and as one can observe, the chocolate-brown spores are about the same size i.e. 10-15 µm.
Click the image to open it to full size in a separate window. And keep in mind this is just a crop of the entire frame.
