Here's why:

* Different species: Trees and flowers belong to different plant species (and even different kingdoms, depending on how you classify).

* Reproductive mechanisms: Trees and flowers have different reproductive mechanisms. Trees generally reproduce through seeds, while flowers might reproduce via seeds, bulbs, or other methods.

* Genetic incompatibility: Their DNA is too different for them to produce fertile offspring.

Think of it like trying to crossbreed a dog and a cat. It's just not possible!