Wild ginger thrives in the shade of the bush, but it is a serious weed, forming thick mattes of rhizomes and suffocating all other plant life. Birds spread the seeds widely.
From the Landcare Research website: Wild ginger (Hedychium gardnerianum), also known as Kahili ginger, was originally grown in New Zealand as a garden plant. It was first found in the wild in the 1940s, and is now a serious weed in native bush, forming dense stands that smother plants and prevent native seedling regeneration. The weed is most troublesome in North Island forests and the warm northern regions of the South Island. It is equally destructive in Hawaii, where it has invaded native Hawaiian rain forests.