SRD said:Note: The effects of the spell may be altered somewhat, based on the nature of the entangling plants.
It is a bit ridiculous to try and use Entangle in, say, a dungeon corridor or in a fine church, or on top of a barren mountain. My DM has never bought into the "underground roots!" argument and I don't blame him one bit. Entangle is very powerful in the right situation. Not everywhere. Otherwise, it could pretty much ruin many otherwise balanced scenarios.
My DM has never bought into the "underground roots!" argument
I agree with this. Even sparse grass is enough for the spell to work, in my opinion, but an area with no visible plant life won't suffice.It is a bit ridiculous to try and use Entangle in, say, a dungeon corridor or in a fine church, or on top of a barren mountain.
Then it is extraordinarily poor design.
Area: Plants in a 40-ft.-radius spread