Minecraft/Cactus

Cactus
Flammable	no
Falls	no
Blast Resistance	1
Transparent	yes
Luminance	0
Stack	64
Drops	cactus
Drops when using silk touch	cactus
Smelts to	green dye

Prickly, green plants that thrive in extreme heat.

Obtaining

Cacti are found in deserts and badlands.

Use

Cacti have value in simple traps. Placing a wall of them damage mobs that approach. Careful though, those spikes will hurt you and your pets as well.

They also destroy any item thrown onto it. Even diamonds!

Cacti need support, similar to sand, but instead of falling, they break, like sugar cane and bamboo.

Notes

You cannot place cacti directly adjacent to another solid block, but they can be placed diagonally. They can also only be placed on sand and red sand.

Automatic farming

Automatic farming allows you to generate an endless supply of items without needing to interact with it in any way.

Taking advantage of cacti breaking if next to a block, a piston can be used and when activated, its head would touch, not push, the cactus.

The tricky bit is detecting when it is time to harvest. Some forget that a block can still be placed on top of a cactus block. So, if you place an observer 3 blocks above the sand of a cactus, when it grows, the observer will emit a redstone charge, which should be used to power a piston. If you grow multiple cacti this way, one observer could power every piston. Use hoppers or flowing water to pick up the cacti and place it into a chest. Don't get rid of the bottom block of cacti, or the cactus will stop growing.