When you burn any of the tall flowers (Lilac, Sunflower, Rose Bush, Peony) or Tall Grass (Here the same CAN happen with seeds) they will drop if they are destroyed by having the top block burnt down. If the bottom block burns down they will get destroyed normally without dropping anything.

What I expected to happen was...:
It doesn't matter which block of these double-block flowers burns down - They will all get destroyed upon burning down.

What actually happened was...:
If the TOP block burns down, the flowers will drop themselves (Tall Grass will eventually drop seeds).

Steps to Reproduce:
1. Put down any of the tall flowers or tall grass (here you might have to try it a few times).
2. Burn their top block by using flint and steel.
3. See how these flowers drop themselves.
Optional 4. Try the same but burn the bottom block. The flowers won't drop.