The Hiroshima Botanical Garden has a fantastic collection of plants from around the world, the most impressive and new to me was the Boabab tree (above). It is a massive plant and this one was proudly displayed from Australia in one of the large greenhouses. This alone was worth the trip at only 510 yen for admission.
Because it is Christmas time, the garden stays open late for park goers to enjoy the Christmas lights and rotating concert series held in the theater. It is also a rare time to see Hiroshima from the garden's observation deck at night. But I am sure that during the day it is quite beautiful as well. There is a shuttle that runs from Itsukaichi stiation that was free when I visited, but be prepared to take a local bus about 25 minutes.
During the different seasons, expect to see the cherry blossoms filling the park. And the walkway to the observation deck will have its wisteria bloom. The rose garden will open during it's peaking season, but the Jurrasic Park Christmas lights stole the show outside for me!