But then where would the spider go?
I think games which design 4 elements as separate often lead into this issue - more games should start creating Storm and Magma trees so people wont feel a need for identical trees!
But ultimately, geomancer needs it's own identity, and there's no reason to give it a level 1 dps spell when it has a summon there (as well as a summon later on, no one else gets a level 1 summon).
You don't have to use poison damage, you just don't get to play earth with level 1 rocks.