Right at the onset of the flavor text "While each ghoran could perpetuate itself via a single immortal seed, the inability to grow or propagate their species ensured that no new ghorans would ever appear."
then
"A ghoran has a deep cavity within its belly, housing a single seed the size of a balled human fist. Roughly every 20 years, a ghoran’s body becomes decrepit enough to no longer function. The ghoran imprints its abilities and memories into this seed and then plants it in the ground. After 1 to 2 months, a new ghoran body is born from the seed, the consciousness from the original transferring over to the fully grown body and leaving the old body behind as a mindless mass of inert plant matter. In this way, a ghoran’s legacy lives on with every regrowth; while the body regenerates, the inner self and memories of the past endure."
"Seed (Ex): As a full-round action, a ghoran can expel the seed from an orifice in its abdomen. If planted in fertile ground and left undisturbed for 2d6 days, the seed grows into a healthy duplicate of the original ghoran, save that the duplicate can reallocate all skill ranks upon sprouting. Once a ghoran expels this seed, it gains 1 negative level, and it dies as soon as the duplicate sprouts. This duplicate replaces the previous ghoran character."
so in fact the new ghoran from seed is the same ghoran that died, just younger and possibly with changed skills.
A resurrection is going to preserve the last skill set arrangement using the piece of the creature you have. He's lucky resurrection works on plants.
If you just threw some dirt on him the seed would grow and he'd likely come back. You'd only need resurrection if the seed had been cracked when eaten (it could pass and then regrow).
It's well known that if you recreate a body but the soul is "in use", you just have a soulless husk that will die soon, that's why you need Clone spell or magic to keep that Manshoon husk alive.
