david weaver
Curly cherry is the only thing that I've ever planed that required me to set the cap iron close on a jack plane.

I guess cocobolo could cause that, too, but I've never planed a really large piece of cocobolo.

Curly maple gets talked about a lot, but quartered curly cherry is far harder to plane cleanly. Agree on the DF, too - it has the nasty combination of potentially hard earlywood and very fragile latewood.