Incremental Merkle Trees

How do Incremental Merkle Trees differ from standard ones?

Standard Merkle Trees require that they need to be complete. That is they must have a value for every single node so that the transaction root can be properly constructed. Incremental Merkle Trees however construct themselves so that there can be 0 values for nodes as well as hash values

Drawbacks

Incremental Merkle Trees allow for easy appending of data but make it impossible to update existing leaves