Still into my "smutty" endeavours ... It turns out the Arrowhead Smut Doassansia sagittariae is not rare at all, as I continue to make new finds of it on my regional trips. Among the few smut fungi that specialise on aquatic plants, D. sagittariae has the advantage of being easily detectable without any rigid sampling procedure or microscopic examination. The leaf spots it causes are very distinct. Below is a sample series showing various degrees on parasitic infection, from very light to heavy.
Admittedly making such documentary images doesn't constitute much of a challenge and in this case I simply used my Epson V600 scanner to make the image directly. However the task has to be done, challenge or not.