From Bulbapedia, the community-driven Pokémon encyclopedia.
A time flower (Japanese: 時間の花 Time Flower) is a crystalized flower that grows in and around the Tree of Beginning. It appeared in the movie, Lucario and the Mystery of Mew.
It is unknown if they are actual flowers, or of the same type of living crystal that makes up the Tree of Beginning. It has the ability to record events and play them at a later date as a holographic image along with sound, if it is stimulated by the right aura. In this way, they are almost like living time capsules or natural cameras. So far, the only ones known to be able to activate them are Sir Aaron, Lucario, and Ash Ketchum.
In the TCG
The time flower appeared as a card in the TCG: