It could most likely be mimiced by a Summon Monster/Natures Ally spell of the approiate level. Or design a new one based on those guidelines. Something like...
Sticks to Snakes
Transmutation
Casting Time: 1 Standard Action
Duration: 1 round per level
Level: Clr 3?
Effect: One or more creatures, no two of which can be more than 30 ft. apart
When you throw down a large staff from your hands upon completion of this spell, it transforms into either a medium constricter or a medium viper for the duration of the spell. At the end of the spell it changes back to its staff form.
Alternativly, you can also cast down a handfull of small sticks, and 1d4+1 of them will turn into tiny vipers.