Smut Fungus
Sphacelotheca or Microbotryum ?
Observed in a marshy area near Eldoret, Kenya, April 2013. Host plant is a kind of Knotweed, probably Persicaria lapathifolia)", f. Polygonaceae.
The growths emerging from these flowering spikes of knotweed at left will release black teleo-spores as a fine powder resembling printer toner. The word 'smut' comes from the German word for dirt. The full life history leading to new plant infections involves a mating of compatible haploid spores. Probably very little is known about this species and its host plant specificity.