Field of Science

Friday Fabulous Flower - Kahili ginger

The Phactors are back home in Lincolnland greeted back from Hawaii by a snow storm, which is somehow fitting. So as jet lag wanes, and our lives get caught up, TPP is happy to be only one day late with the FFF. One of the more notable things about Hawaii biologically is, unfortunately, the prominence of invasive species. And none are more troublesome or more handsome than Kahili ginger (Hedychium gardnerianum), an ornamental species from Asia. This ginger forms almost impenetrable stands in the forest understory shading out native species.  And the massive rhizomes form dense mats preventing anything else from taking root.  In flower the 4-6' tall aerial shoots have terminal inflorescences of yellow-orange flowers that smell quite wonderful. The tan-colored fruits that follow are sort of nondescript until the fruits open revealing bright orange aril-covered seeds.  That's what's being shown in this image; flowers at the stage of seed dispersal.  Amusingly it makes the fern sort of look like an angiosperm.  The arils are both a visual attractant and a reward for the bird seed dispersers. So this plant can really get around.
Getting rid of such a plant is quite a chore, if not nearly impossible. Not knowing what is recommended, TPP suspects it takes cutting off the stand of aerial shoots, no small task, and then spraying the remaining stalks and rhizomes with an herbicide to prevent regrowth.  The idea of chopping out such a stand by hand sounds almost impossible, and reminds TPP of some of the worst gardening disasters of his experience on steroids. 


Maire Smith said...

I had success with a patch of this plant, chopping into all the fleshy bits I could find near the ground, with a machete, and then painting the cuts with weedkiller. They died nicely.

The Phytophactor said...

Dear Maire,
Thank you for the tip. Readers note: Gingers are monocots so lawn weed killers that target dicots won't work, you have to use a general plant killer, so applying it with a brush, literally painting it on, is a safer (for other plants) way to spot treat than spraying.