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Trees are the largest plants in Terraria, appearing mostly at the surface and often in clusters with similar height. Trees can be chopped down with an axe, with the use of explosives, or by pouring lava on the base. Destroying or chopping a tree will yield many units of wood, an essential crafting material, and give a chance of dropping one or more acorns that can be planted to grow more trees. Larger trees will yield more of these two materials when removed, since the amount of wood and acorns obtained from a tree depends on its size: one unit of wood will drop for each block of tree (including branches), and one acorn may drop for each leaf patch instead of wood, excluding the top patch of leaves. It is possible to cut off parts of the tree, but cutting at the lowermost center tile will destroy the entire tree. If parts of the tree are left, they will not regrow. Tiles beneath trees cannot be destroyed while the tree stands.
Trees as obstacles
With the exception of Living Trees (discussed further below), trees are background objects that do not affect player or monster movement.
Trees cannot be climbed or scaled with items such as a grappling hook, nor can blocks of dirt or other walk-on surfaces be placed to overlap their limbs or foliage. It can sometimes be necessary to chop down a tree that is next to a cavern entrance or cliff in the early game in order to replace it with a ladder of blocks that will allow scaling of the steep surface; this becomes unnecessary when the player obtains a grappling hook, Climbing Claws or other items that allows improved jumping or flying.
Trees must be removed when building houses that overlap the space they cover or when digging up from underground to exit to the surface.
Planting an acorn in grass will create a Sapling that will eventually grow into a tree of a random size and shape. Saplings can only grow under the following conditions:
- An acorn can only be planted on a dirt block covered with grass, corrupt grass, crimson grass, hallowed grass, a mud block covered with jungle grass, on snow, or on sand.
- The acorn requires one horizontal space of open ground to either side.
- There must be at least three open tiles between saplings or only one will grow into a tree. This matches the previous rule, i.e. each acorn needs both adjacent tiles free, which means the closest two trees can be is with three tiles between them.
- The acorn requires at least 32 feet (i.e. 16 tiles) of vertical clearance to grow into a tree (e.g, if you are planting an acorn at 300 feet above, there may only be blocks at 332 feet or higher directly above it in order for it to grow into a tree). Jungle trees need 24 tiles and palms need 30.
- An acorn will not grow indoors - all background walls or overhanging ledges must be removed, and if you have a ceiling it must be at least 32 feet above the block where the acorn was planted as measured by a Depth Meter.
- Acorns will not grow in the presence of torches, wood platforms or sunflowers within its 2-block radius.
- Saplings must be off-screen in order to become trees. They will not grow when currently in view, unlike most other plants which can spawn while you watch.
Forest trees are the most common type. They yield regular Wood when harvested. Many Forest trees eventually turn into Corrupted, Crimson or Hallowed ones when the area they grow on is overtaken by these biomes. This is the only type of tree that can have several types of foliage.
Corrupt & Crimson trees
Corrupt trees are purple trees only found where there is Corruption. They behave like normal trees, but drop Ebonwood. They are converted from normal trees when corruption spreads upon them. Crimson trees are red trees only found where there is Crimson. They behave like normal trees, but drop Shadewood. They are converted from normal trees when crimson spreads upon them. It is possible to convert both into normal trees again by using Purification Powder on them.
As of 188.8.131.52, like all other trees, Corrupt and Crimson trees can be planted using acorns in corrupted or crimson grass, following the same rules as trees grown in grass. On the console and mobile versions, Corrupt and Crimson trees cannot be grown as of yet.
Jungle trees are found in the Jungle and another variant appears in the Underground Jungle. They spawn randomly or can be planted on jungle grass wide enough for a tree to grow on, and may also spawn under water. Jungle trees also grow higher than normal trees: up to 21 blocks. Jungle trees drop Rich Mahogany wood.
In hardmode, Corruption spreads through mud, replacing it with dirt, and jungle trees turn into corrupt trees. Sadly, because cleaning Corruption will turn a corrupt tree into a normal tree, jungle trees are lost forever when they become corrupt.
Since Jungle trees are competing for place with fast growing bushes, a viable method for farming them is to submerge the area in water. Foliage introduced in 1.2 will not grow in water deep enough that fish can spawn, allowing only jungle grass and trees to spawn.
Trees found in the Hallow have a taller and triangle-shaped foliage, and exist in many different colors: blue, red, light green, cyan, pink, magenta, yellow and purple. Normal trees turn into Hallow trees when the Hallow reaches them. Unlike Corrupt, Crimson, and Jungle trees, Hallow trees drop acorns when chopped down.
As of 1.2, Hallow trees drop Pearlwood instead of regular wood.
Palm trees 
Palm Trees are only found naturally in the Ocean biome, but can be planted on any normal Sand Block in any biome using acorns. There are also Corrupt, Crimson and Hallow variants, which drop ebon-, shade-, or pearlwood respectively, rather than palm wood. Palm trees will not drop acorns. Unlike other trees, palm trees require to be planted on only one block of sand, and only one space is needed between the seed and another object for the tree to grow.
See article: Living Tree
Living Trees are huge trees that can be found in the Overworld and are created during world creation. Unlike regular Trees, Living Trees are quite large, reaching high into the air (on Small worlds they can extend into the range of Harpies), with their trunks being several tiles wide. They are also not background items like normal trees, meaning that in order to pass them, a player must tunnel through them, go underneath them, or go over them.
Giant Glowing Mushrooms
See article: Giant glowing mushroom
These "trees" are different from others because they take the form of a Giant glowing mushroom, but are treated by the game as trees when they grow on the surface. Unlike the other kinds of trees, they cannot be planted. Surface mushroom trees grow on mushroom grass above sea level in a similar way to jungle trees, and can grow branches. When cut down, they will drop glowing mushrooms rather than wood. They do not drop acorns or mushroom grass seeds on the surface. Underground giant mushrooms are different in that they do not always drop glowing mushrooms, and they sometimes drop mushroom grass seeds. They have a different appearance and cannot grow with branches.
- Lava will instantly destroy trees.
- Up until 1.2, trees only grew on the surface. A new variety of smaller Jungle trees can be found underground now.
- The underground contains giant glowing mushrooms, which are cut like trees but yield glowing mushrooms instead of wood when harvested.
- It is possible to attach torches to the trunk of a tree, except palm trees.
- 184.108.40.206: Fixed bug where trees won't grow behind biome Wooden Fences.
- Palm trees introduced.
- Snowy trees now drop Boreal wood.
- Acorns can now be planted on all types of grass.
- Replaced Tree 9's graphic.
- Living Trees introduced.
- Multi-colored wood introduced.
- Variations on the normal tree top sprites added.
- 1.1.1: Snowy trees introduced.
- Trees grow 1 block higher and jungle trees grow another 5 blocks higher.
- Hallow trees introduced.
- Tall grass and flowers no longer obstruct tree growth, making trimming the grass unnecessary.
- Acorn saplings require 2 tiles between saplings to grow instead of 3.
- 1.0.5: Corrupt and Jungle trees no longer drop acorns.
- 1.0.4: Jungle trees added.
- 1.0.3: Trees become corrupt when corruption reaches them instead of being destroyed. And the new corrupt trees become un-corrupted upon purification.
- Pre-Release: Introduced.