Oak saplings growing spruce trees.

I planted oak saplings and they grew into Spruce trees.
I expected Oak trees to grow.

Steps to Reproduce:
Growing trees in a Jungle Forrest Biome.
(I don't know whether the biome has anything to do with it)
I collected the drops from harvesting both spruce and oak trees. Both trees types grow the leaves of both spruce and oak leaves. The spruce leaves produce spruce saplings and the oak leaves produce oak saplings but they will grow into spruce trees. I even threw away all my oak saplings and harvested only the oak saplings off of this oak tree and planted them they still produced spruce trees.