Your subject's skin splits open, revealing wood and bark.

Leaves sprout from his limbs even as he starts to grow.

You transform the subject of the spell into a Huge oak tree.

For a number of days equal to your caster level, that oak tree animates as a treant (though it can't animate trees) and serves as you command.

You can either command it to follow you, or you can leave it somewhere with a triggering phrase as described in the liveoak spell (PH 248).

When the spell's duration expires, the subject becomes in all respects a normal tree, taking root where it stands if capable.

A creature that succeeds on its saving throw is instead slowed (as the spell) as his body fights off the transformation from within.

When the spell's duration expires, the subject returns to normal.