Well, big Al... those other trees are called Bark Horrors
, and by killing them I managed to procure (is that the right word for it?) three seeds. They look just like Oakenmir, but are a lot less friendly
The nifty thing about them is that they can respawn, so if you don't get enough seeds the first time, try a visit later on.
Klick
here for a hint on location of the Bark Horrors.
Cheers // Jazzid