About 3% to 3.6% of Earth’s total land area is islands and in the Pacific Ocean there are about 25,000. One in six of the world’s known plant species occur on them. The Pacific harbors one the largest biodiversity hot spots.
The Polynesian-Micronesian Hotspot, which Hawaii is a part of, is about the size of Switzerland and has thousands of native ferns and flowering plants. Half are endemic, meaning they are only found there. Human activity threatens many of these species and there is the potential for a net loss of global biodiversity.
Possessing a greater appreciation of the flora of Hawaii can lend a hand in its preservation. To celebrate and honor the native flora, we would like to introduce three native plants you might consider for your garden.
Ohia, or Metrosideros polymorpha, makes up about 50% of all trees in the state. These trees range from mauka to makai and can even be found on new lava flows. Currently, this keystone species is afflicted with rapid ohia death, which is caused by a lethal Ceratocystis fungus. The need to plant these trees now is more urgent than ever. You should know the trees start quickly from seed but may take quite a while to get to planting size.
Plants produced through vegetative propagation are desirable. These clones have a shortened juvenile stage and consistent flower color. Patient gardeners will be rewarded with a beautiful tree with blossoms ranging from yellow to red. The new growth, or liko, are often red with white hairs on the underside of the leaf.
Endemic palms trees can be recognized by their iconic leaves. Fan palms are hard to miss with their large fronds that sway in the trade breezes. There are about 29 species of Pritchardia, or loulu, in the Pacific with 25 that can be found here in Hawaii. Curiously many of these palms that we see in green spaces are taxa native to Fiji. Pritchardia martii is endemic to Oahu and once formed forests that covered the Ewa Plain. Now they can be seen along the high elevation, wind-swept, ridges. Unfortunately, their seeds are irresistible to rats. If you plant one in your yard and want to save the seeds remove the fruit before they turn from green to black.
Our final plant is a shrub with an emblematic flower: Hibiscus. They are seen everywhere from topical print fabrics to landscaping. Generally, most species we see are non-native. However, there is one yellow, and several white- and red-flowered taxa that are native. The yellow species, Hibiscus brackenridgei (mao hau hele) is the state flower.
A yellow cultivar of Hibiscus rosa-sinensis is often mistaken for the state flower. While the species are similar, the leaves and stamen are different when closely examined. The stamen is in the center of the flower, encircled by the petals.
You can find this native species at local botanical gardens. However, it seems to be underutilized in private gardens.
Since all these plants are not common in the gardens of Hawaii, where can you purchase them?
Hui Ku Maoli Ola in Kaneohe specializes in native Hawaiian plants and is currently open. Home Depot also stocks some native plants.
An excellent reference for growing native plants is Kerin Lilleeng-Rosenberger’s “Growing Hawaii’s Native Plants.”
By planting ethically obtained native plants, you can help the species thrive despite threats by invasive species and habitat degradation. If you don’t have space in your garden, consider volunteering with local conservation organizations once it’s safe to do so.
Jesse Adams and Tim Kroessig are both botanists at the Harold L. Lyon Arboretum, where they work to catalogue, propagate and conserve the plant diversity found there.
