This large, clump-forming grass is one of the fastest growing terrestrial plants in the world—growing 4” a day and up to 20 feet tall! Arundo donax is also known as “giant reed.”
Arundo grows in wet areas, including wetlands and along ditches and streams, forming impenetrable thickets that can cover several acres as a single colony with one underground rhizome or root mass. It crowds out other plants, dramatically alters native habitat, impedes water flow and promotes flooding, and also ignites easily and promotes intense fires. This plant spreads aggressively and reproduces quickly. In arid locations it out-competes other plants for available water.
Recognize giant reed by its stiff leaves with a clasping connection to the stem and small hairs along the margins which are felt when the leaf is rubbed in the wrong direction. The leaves are alternately arranged on the stem and all in one horizontal plane (“flat” from side to side). Sugar cane looks a bit similar, but sugar cane leaves are opposite (i.e., attach to the stem in pairs at the same level) instead of alternating, and do not have the clasping connection.
Arundo is native to temperate and tropical Asia and has spread widely to many parts of the world with similar climate. This invader is spreading on Kauai at several known locations, mostly on the west side.
This plant is on the Pono black list and is also a KISC target — KISC is actively working to control it on Kauai.
Please do not plant giant reed. Kauai’s Pono-endorsed landscapers and nursery professionals can recommend non-invasive alternatives for your garden. Mahalo!
- More info from Invasive Species Compendium (CABI)
- More info from Hawaii Invasive Species Council (HISC)
- More info from KISC