"A demonic plant? Don't be daft, go research something useful to society."
"But-but the p-plant! It's evil! It must be destroyed!"
"Now the flowers bloom all year round thanks to the most holy Spirit of Urban flora. It just takes a little blood."
Magic is the lifeforce of all living creatures, and it is from it that all life is made - in areas with lots of undead, magic might actually be missing or weak, which puts a whole new spin on how dangerous the undead are. Even simple zombies can be troublesome if you're relying on mages and you hit a pocket of undead making a low-magic zone...