This is what someone wants to do
Have a Ghoran Vamp. so here is Vetala. My ? is with the type change, does the Ghoran stop being a plant type to become an undead? or is it both? If it does become only an undead, does it drop its plant type features?
Vetala" is an acquired template that can be added to any living creature with 5 or more Hit Dice (referred to hereafter as the base creature). Most vetalas were once humanoids, fey, or monstrous humanoids. A vetala uses the base creature's stats and abilities except as noted here.
CR: Same as the base creature + 2.
Alignment: Any evil.
Type: The creature's type changes to undead (augmented). Do not recalculate class Hit Dice, BAB, or saves.
|I'm Hiding In Your Closet|
Create Spawn (Su): A vampire can create spawn out of those it slays with blood drain or energy drain, provided that the slain creature is of
the same creature type as the vampire’s base creature type.
You got to be one to make one. So, humanoid vampires can drain a ghoran but won't create spawn from one.
Look for an evil power who has plant and undead domains. Their priest could create the original ghoran vampire.