I don't remember ever seeing these before. I looked them up and their name matches their unusual flower shape, bottlebrush. In full bloom they are quite striking.

According to Gardenguides.com the bottlebrush tree (Callistemon citrinus) is an evergreen shrub native to Australia but widely grown in southern California and Florida. Apparently they will survive up in Savannah as well. The long lasting blooms are very popular with birds and insects, especially hummingbirds, and appear in the spring and summer.