Cactus

Cactus (plural Cacti) is a block that is found naturally on deserts. When any entity, including players and mobs, touches a cactus, of damage is taken (damage is dealt every 0.5 second). The block can be harvested easily by either mining the block underneath, making that block fall, or directly by hand safely if the player body does not come in contact with it.

The block has one texture put on all vertical sides of the block, with another on top, and a third on the bottom (which looks like a simpler version of logs).

Cacti will destroy any items that come into contact with them, including harvested cacti blocks. If a player or mob dies by cacti, it is possible that many of their dropped items will be destroyed. Therefore, making traps with cacti in order to farm resources can be less efficient. As it can destroy the items that contacted with the cactus, cactus can be used to make garbage bins as it deals less damage than lava when touched.

Cactus can be cooked in a Furnace to make cactus green dye.

Growing conditions
Cacti grow only on Sand to a maximum height of three blocks, though higher stacks can be placed by the player. Cacti are most common in desert biomes, but can rarely be found on a beach in other biomes. Cacti can only be placed either on sand or on other cactus blocks, with no horizontally adjacent solid blocks. Bone meal does not work on cacti and won't speed their growth. Cacti cannot be placed onto Sandstone despite the similar name.

When the spot a cactus is placed in becomes unsuitable, such as a block is placed next to them or their own sand block underneath is harvested or falls, the cactus block and any above it collapse into blocks that can be collected and placed again.

Cacti can be placed underwater, provided they are placed on sand, and will grow if they break the surface. Cacti placed in a one-block depth of water will grow normally. A two-block cacti stack placed at a two-block depth will grow to the three-block height. Any higher stacks at greater depths will need to be placed entirely by the player. An interesting use of this is that since cactus blocks are transparent, high stacks of them that break the surface can be used to extend sunlight deep underwater.

Cacti do not need light to grow and are non-flammable. As such, they grow well in the Nether, provided the player also brings in sand.

History
Cacti were first seen in Alpha 1.0.6.

Before Alpha 1.0.11:
 * Cacti could be placed anywhere, and did not have the requirement that the space around it be empty. This allowed cacti to be placed to form a damaging floor: both players and mobs take half a heart of damage when they walk on a cactus block. This made it useful for traps, such as a hallway with a cactus block floor that would kill all mobs that walked on it.
 * Collecting cacti hurt the player.
 * The texture was different and didn't have spines. Cactus-Pre Alpha 1.0.11.png

Farming
It is possible to make a fully automated cactus farm, which when complete, requires no further effort from the player to harvest the resources, also shown here.

Cactus defense
Due to their ability to damage entities and automatic growth, cacti can make a barrier around safe locations if a player can dedicate a few days of game time to deploying them properly. There are pros and cons to using a cactus wall, and are best placed as a secondary wall around a well lit fenced area.


 * Cacti are higher than fences and can block the arrows from skeletons. Unlike fences, however, a player cannot see beyond them.


 * Creepers and zombies may walk into a wall of cacti and injure themselves while attempting to attack a player. This can now be almost impossible because they have a path-finding AI since 12w03a.


 * Cacti grow with no supervision, and a player doesn't need to search out in the wilderness for more materials to extend the wall. However, they will grow at their own rate and cannot be sped along.


 * Cacti acts as a disposal, allowing players to destroy items by throwing it into the cacti.


 * Torches cannot be attached to cacti. Instead, torches must be set into the sand between cacti or along a separate fence.


 * Passive mobs will frequently wander into a cactus wall and die. This is more common in a vertical or horizontal setup, as they may find themselves blocked on three sides. This may make gathering their loot easier if the cacti don't destroy whatever they end up dropping.

Because they cannot be adjacent to any other solid block, a cactus wall must be built diagonally or in a zigzag pattern two blocks thick. To extend the wall, a player needs only cut down the top two blocks from a cactus and place them elsewhere. Unfortunately, some cactus items may be lost to the damaging effect of other cacti nearby.

In some rare situations mobs can get onto a single cacti block, not by pathfinding but when jostled by other mobs or when aggravated by the player. Since the damage likely won't kill it instantly they can then jump on to a neighbouring fence or reach otherwise unexpected places (creeper trigger distance, skeleton line-of-sight etc). Therefore in risk areas one might not want to wait for natural growth of the seed block and stack two or three cacti blocks at once.

A good defense is a large zigzag square, expanding it as you go along, only wanting the seed block. This will make a large deadly square that mobs wander into (Before improved AI).

Bugs

 * A cactus can be found floating, like sand. This is however very rare, and mostly happens in multiplayer.
 * A cactus can be placed by an Enderman on any block.(but will not grow)
 * In multiplayer, a cactus can be in a different location from what another player sees. Both players' cacti will still hurt one another, though.

Trivia

 * Cactus use the same sound files as wool when breaking and placing.
 * Until Beta 1.8, when dropped onto the world, the Cactus item is slightly larger than most other blocks despite the fact that they are visibly smaller when placed.
 * When a minecart hits a cactus block, the minecart is destroyed and dropped (the item instance of the minecart is also often destroyed).
 * Cactus can be placed next to saplings, but the cactus will break when the tree grows.
 * Cacti blocks aren't flammable.
 * Cacti can be useful for "sewage systems."
 * Cacti are based on the Saguaro cactus, native to the Sonoran Desert in Southwestern United States and Northern Mexico.
 * Placing iron bars on top of a single cactus will cause only the corners to damage.
 * When Endermen pick cactus blocks, they don't usually pick the bottom block; they "pollinate" it.
 * The bottom of Cactus is the same texture of a tree's bottom and top, but light green.

Gallery
Kaktus Cactus Cactus 선인장 Cactus Kaktus Кактус 仙人掌