sooby,
This may sound like cheating, but have you contacted the public garden where you saw these plants to ask them for the identity of this plant? Your call may get transferred to several different people, but I think you could obtain the answer by doing this.
Other than that I am thinking that rather than drive all the way over there to take new photos, can you contact a friend in that area who may take the photos for you? Sometimes you can contact a garden club and they may help you...heck, they may even know the name of the plant.
