They cannot be defeated with a spin or slide due to the spikes they have guarding their entire lower half, but once Crash gets close enough to them, they will hide themselves around their spikes and cover their heads. At this point Crash can easily finish them off with a belly flop (as jumping on them just causes Crash to bounce). In order to access the secret entrance to Road to Ruin via the secret warp room, one of the spitter plants must be defeated with a belly flop.
Crash can also defeat them by digging underneath them and spinning them. They drop nine wumpa fruit after being defeated with a body slam, or being run into by Crash and defeated by Aku Aku. However, they do not drop any wumpa fruit when being spun from underneath.
A Spitter Plant in Crash Bandicoot 2: Cortex Strikes Back.