ʻŌhiʻa ʻai, mountain apple, is an introduced species and one of the thousands of plants in Hawaiʻi that are harmless. Photo by Forest and Kim Starr.
The vast majority of introduced plants stay in the gardens where they are planted. Without their native pollinators or preferred climate, their survival and spread depends on humans. Our careful maintenance keeps them going. Take breadfruit and citrus trees—they flower and fruit in Hawaiʻi, but can’t set seed and therefore don’t spread in the wild. If you want these plants, you have to cultivate them.
A small subset of introduced plants spread without human help. “Of the roughly 12 to 13,000 non-native plants present in Hawaiʻi, only about 12% have become naturalized, or have formed self-sustaining populations in the wild,” explains Chuck Chimera, the Weed Risk Assessment specialist with the University of Hawaiʻi.
Plumeria is one of the 12-13,000 plants introduced to Hawaiʻi. Plumeria do not produce seed and therefore never escaped cultivation. Photo by Forest and Kim Starr.
Naturalized, non-native species are those we regularly see hiking or driving down the road; they are the plants in the unmanaged parts of the land; spreading without our help, forming self-sustaining populations that will persist year after year. Sometimes, we take notice of them: like a mountain apple along the roadside. Sometimes we overlook them, like self-heal, a small, purple flowered plant in the mint family – it grows from the lowlands to around 8000ʻ, given enough water.
ʻŌhiʻa ʻai flowers in the forest are a sight to appreciate. Photo by Forest and Kim Starr.
Introduced plants or animals often provide a service to us or to the environment: Cook pines collect water from passing clouds, sweet potato and citrus fill our bellies, wild hives of European honeybees pollinate our gardens, and red-billed leothrix spread the seeds of native plants.
Self-heal, Prunella vulgaris, is a common introduced plant in Hawaiʻi. Photo by Forest and Kim Starr.
It is only tiny subset, roughly 1% of all the introduced species, that spread aggressively and outcompete native Hawaiian plants. Capable of transforming our ecosystems, these are the invasive species that land managers battle. Miconia, fountain grass, little fire ants, and strawberry guava are among the most notorious. While these bad actors get a lot of attention, most foreign introductions are benign, and even provide benefits to us.
Take time to appreciate the beauty and savor the tastes of all the introduced species that abound. A Valentines bouquet of locally grown flowers, a meal of fresh fish on a bed of locally grown greens, haupia for dessert. Support your neighborhood farmer or flower grower at a farmers market or grocer. Doing so helps prevent the accidental interisland spread of hitchiking pests like little fire ants or coqui frogs.
Please make wise planting decisions; check before you plant. The Weed Risk Assesment is 95% accurate at predicting the liklihood of a plant becoming invasive in Hawaiʻi. Check it out at plantpono.org
Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.
Originally published in the Maui News on February 12th, 2017 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.
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