Costus dubius is one unmistakable plant. I found the common name Green Grenade Ginger on Flickr and found it rather humorous but extremely apt! The bulb-like structure that bears the flowers does look like a grenade!
Costus used to be part of the ginger family. However, there are some small differences in the floral structure and also members of the Costaceae do not have the same aromatic oils so characteristic of real gingers.