Whenever Sprouting Phytohydra is dealt damage, you may put a token that's a copy of Sprouting Phytohydra onto the battlefield.1 A hydra tender's problem isn't having enough defenses but enough pots.
Illus. Heather Hudson
5/1/2006: A token copy of Sprouting Phytohydra is created even if the damage dealt to Sprouting Phytohydra destroys it.
5/1/2006: If a token copy of Sprouting Phytohydra is dealt damage, it will create another token copy.
5/1/2006: If Cytoshape turns a creature into a copy of Sprouting Phytohydra, and that creature is dealt damage, the token that is put onto the battlefield is simply a copy of Sprouting Phytohydra. At the end of the turn, the Cytoshaped creature will revert back to what it was, but the token copying it will not.