Minecraft wiki entry for Cactus, associated text: Naturally generated cacti
Naturally occurring cacti in a badlands biome.
The bottom of a cactus seen with the "floating cactus" bug (see below).
Natural cactus generated against a village house.
Natural "ghost cactus" on sand block.
Cactus generated on stone due to a lava lake.
This view shows the white bottom texture of the cactus (item).