The Machete is a key item necessary to go through the smaller patch of flowers and enter the Witch's House. It is found in the Rose Patch, marked by a silver light. In Extra Mode, it is found in the rotting log by the start. The in-game description for the Machete says "A good tool for cutting. Rusty and old."
The Machete is used to cut the smaller patch of roses, thus leading to the Witch's House. Upon using the Machete, the Machete will break.
The Machete cannot cut through the big patch of roses at the bottom, trying to cut through the big roses will give out a message saying, "Can't even make a dent in them." Try to cut through the big patch in Extra Mode, and the machete blade will break off and fly into Viola's eye, killing her.