Topiary Plant
Here is an oddity among the wilds, a small thorny bush trimmed to resemble a dog. This is actually a living creature and if the party looks away, when they look back the bush appears to have moved, although at the moment it is motionless.
This is a topiary plant, a strange scavenger that can adopt the shape of anything it consumes, gaining 1 hit point per hit die of its prey, The plant's hit dice equal one-fourth of its hit points. A topiary plant may grow no larger than 0 [sic] hit dice. It takes one turn for a topiary plant to alter its shape. This plant is non-aggressive, preferring dead prey to living. Its thorns exude a weak poison (save at +4 to avoid its effects).
Any druid with a speak with plants spell may befriend this plant for one day.