Cactus

This plant is found in the desert. When cut down with an axe it yields varying amounts of cactus(drop) similar to the way a tree drops wood. Deals 10 damage to the player when touched. They range from 1- 10 blocks high. The cactus grows over time, starting as a 1 block high clump. Each branch on a cactus cannot grow outwards more than 1 block, but they can grow upwards until they reach 10 blocks from the base- they can be taller than the stalk! There are no Cactus seeds, as cacti can only be found in deserts. Cacti is one of the few objects in the game that you can walk through, and by using it properly, you can reach the speed to activate Hermes' Boots. Make sure you are not wearing a Cobalt Shield, then run onto cacti. If the knockback sends you forwards, you will have enough speed to follow through and activate the Hermes' Boots.

Destroying the sand underneath a Cacti will immediately destroy the entire Cactus above it. This makes clearing a field of Cactus, as well as harvesting them, a breeze considering each cactus is rooted on a single block.

When cacti grow, they will break any block above them. Make sure to have a high ceiling when making a cactus farm.

Cacti are used in alchemy to craft Swiftness Potions and Thorns Potions.

Trivia
Cacti were added in update 1.0.5.

Cacti are one of the only objects that can damage the player, yet can be walked through, sharing this property with only the thorny bushes in Jungle and Corruption biomes.