Mould, a zygomyces. Apophysomyces elegans, A. variabilis, A. trapeziformis, and A. ossiformis.
Found in rotting organic material.
Tends to cause invasive disease in leukemics and their ilk, soft tissue infections in burn patients and after injury with wood/dirt in normal hosts. Usually Apophysomyces elegans.
Necotizing soft tissue infections after trauma in diabetics and after tornado injuries in normal hosts (PubMed) (PubMed). How Dorothy avoided it on the way to Oz is unknown. That scene scared the hell out of me as a kid (childhood fears). My mom says I hid under the kitchen table.