Miconia, Clidemia, and Invasive Amphibians

Some invasive organisms can thrive in the shadowy understory of the Hawaiian wet forests. Miconia (Miconia calvescens) and Clidemia (Miconia crenata, or Clidemia hirta), are native to tropical America. Even though some species are threatened in their native habitat, they have become an invasive threat in other tropical areas. They are especially invasive on Pacific islands. They grow in wet areas, where they quickly dominate and smother other plants. They were introduced to Hawai‘i as botanical specimens and house plants in the 1960s through the 1970s. They escaped cultivation to create infestations on Kaua‘i, O‘ahu, Maui, and Hawai‘i islands.

Miconia grows taller than clidemia and can quickly grow to the size of a small tree. It has large attractive leaves with purple undersides. The large leaves prevent sunlight from reaching any nearby plants. Another environmental hazard of miconia overgrowth is its shallow root systems that can increase the likelihood of erosion and landslides after heavy rainstorms. A mature miconia can produce millions of seeds a year which remain viable for more than a decade. The seeds are contained in small fruit that are eaten and spread by birds.

Clidemia is related to miconia. It has smaller leaves and only grows to the size of a shrub. It is shade tolerant and quickly spreads where the soil has been disturbed. Similar to miconia, clidemia produces abundant fruit with millions of seeds per individual plant. Clidemia often grows together in thickets that quickly take over a large area.

Many introduced amphibians enjoy the same shady wet places as the miconia and clidemia. Living in the shadows is the cane toad (Chaunus marinus, or Bufo marinus). This toad, native to central and south America, was brought to Hawai‘i island in 1932 to control sugar cane borer weevils. This nocturnal poisonous toad can lay up to 20,000 eggs at a time, and live up to 15 years. It can now be found on all main Hawaiian islands.

On top of the Miconia leaf is the noisy coqui frog (Eleutherodactylus coqui). It was introduced to Hawai‘i in 1988 as a hitchhiker in potted plants imported from Puerto Rico. The coqui frog is well loved in its native Puerto Rico for its distinctive “ko-kee!” call at sunset. The population density in Hawai‘i where frogs have established is about double that of their native Puerto Rico. The noise level is also doubled.