Spike Growth/Stone vs. Spell Resistance

[Quasqueton]

Spike Growth and Spike Stones both say "Yes" for spell resistance. How exactly does spell resistance work against these spells? They are transformation spells targeted on the ground, not a creature. Does spell resistance allow a creature to ignore the physical spikes on the ground?

Quasqueton

 

[Pielorinho]

I'm pretty sure that's exactly what it does. If it seems weird, remember that when the spell's duration ends, the stones return to their normal shape; that suggests that for the spell's duration, it's creating a magical field that reshapes the stones. Creatures with SR might temporarily suppress that field where they touch it.

Daniel