An ornamental ginger that escapes gardens to invade Hawaiʻi’s native forests and watersheds. Cultivated in Hawaiʻi since at least 1930, the first records of escape occurred in 1940 in Hawaiʻi Volcanoes National Park. Now weedy on all the main Hawaiian Islands, this ginger is also a pest in the Azores where it has overwhelmed crops and blocked streams.
The invasion is impossible to miss when driving in the Volcano area of Hawaiʻi Island. Right on the roadside was one of the most beautiful native forests in the state, now below a canopy of single aged ohia trees is a thick mat of Hedychium gardnerianum. The blanket of tubers prevents other native vegetation from germinating. The Division of Forestry and Wildlife of the Hawaiʻi Department of Land and Natural Resources has designated this species as one of “Hawaiʻi’s Most Invasive Horticultural Plants.”
Description and Dispersal:
- A coarse ginger with leafy shoots growing up to 6 ft tall
- Leaves (7-17 in long by 4-6 in wide) clasping the tall shoots in an alternate pattern
- Yellow flowers with long red centers grow in spiked cylindrical clusters
- Seeds spread by birds, root fragments will also regrow