There is this one tree (I believe an oak tree) near my road that is very large in size. Practically at the base of its trunk, it diverges into four other large trunks:

Tree split into 4

What causes this phenomenon in trees? Is it possible that this was actually a few trees that have grow into one another? To me, this looks like one tree that early on in it's life, somehow split off into four trunks like so.

  • Coppicing, where you cut trees back to stimulate growth, can cause this. There are natural ways for this to occur, animals, fire, etc.
    – Aravona
    Commented Aug 15, 2017 at 8:27
  • @Aravona so it's possible that many years ago this tree was cut down significantly and managed to grow back into this state?
    – Timmy Jim
    Commented Aug 15, 2017 at 11:12
  • Yes, though some tree like Rowan grow like this anyway, we're constantly having to trim new sprouting trunks off
    – Aravona
    Commented Aug 15, 2017 at 11:21

2 Answers 2


In the US this is sometimes called a schoolmarm (alt school-marm) there are a number of ways they can form. OSHA Logging terms

As mentioned in the existing answer some trees like willow grow very aggressively and a low cut stump can have several shoots that grow in to trees.

Two or more seeds growing in the same location can grow multiple trees. If there is sufficient sunlight neither new sapling will have a significant advantage and both will prosper. This can occur naturally or from manual over planting.

Sometimes two forks of a tree will grow about the same. This can be an internal event for the tree, or due to an external trauma like the top of the main trunk of the sapling being browsed by wild life, leaving lower branches to compete to become one or more primary trunk.

Schoolmarm's pose risks on two fronts.

  1. The junction between the trunks is more likely to catch water and/or debris, leading to rot that will cause it to fail (die and/or fall) earlier then it neighbors.
  2. It is very difficult to cut down the tree safely, without good access to back side of the tree it is difficult to control the direction of it's fall. Directional tree felling

If in the past a fairly large tree had been cut there, the stump, if left high enough to sprout could feasibly have a group that could grow to that size Because it doesn't appear to be from lightning or some other natural damage.

  • Yup. Looks like stump-sprouting to me too. Commented Aug 15, 2017 at 18:42

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