The plant door spell opens a magical portal or passageway through trees, undergrowth, thickets, or any similar growth--even growth of a magical nature. The plant door is open to the caster who cast the spell, casters of a higher level, or dryads; others must be shown the location of the door. The door even enables the caster to enter a solid tree trunk and remain hidden there until the spell ends. The spell also enables the passage or hiding of any man-sized or smaller creature; hiding is subject to space considerations. If the tree is cut down or burned, those within must leave before the tree falls or is consumed, or else they are killed also. If the caster opts to stay within an oak, the spell lasts nine times longer than normal; if within an ash tree, it lasts three times longer. The path created by the spell is up to 4 feet wide, 8 feet high, and 12 feet long. This spell does not function on plant-based monsters (shambling mounds, molds, slimes, treants, etc.).   At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, increase the length of the path by 12 feet for each level above 4th. If cast with a 9th level spell or higher, the duration becomes up to 1 hour instead.