Redwood trees don't replace the saplings they grow from and sometimes grow oddly.

[DefinitelyNotFred]

I'm using Mantle 1.10.2-1.1.5, Natura 1.10.2-4.1.0.80, and Forge 12.18.3.2185 with no other mods installed.

Saplings not being replaced:

Odd growth (at least I assume it's not supposed to happen this way): These things happen to both naturally spawned trees and those grown from saplings. Glowstone added by me of course. The rings of leaves on the base of the trees happens to roughly a third of Redwood trees.