Efloresce or Effloresce: How To spell?

The word Efloresce is misspelled against Effloresce, a verb meaning "To become covered with a whitish crust or light crystallization, from a slow chemical change between some of the ingredients of the matter covered and an acid proceeding commonly from an external source; as, the walls of limestone caverns sometimes effloresce with nitrate of calcium in consequence of the action in consequence of nitric acid formed in the atmosphere."