Family: Dilleniaceae
An invasive flowering shrub. Native to Borneo and Sumatra, shrubby Dillenia thrives in tropical climates. It is invasive in Jamaica, Sri Lanka, and Hawaii.
In Oahu, shrubby dillenia forms monotypic thickets in a wide range of ecosystems – from lowland moist valleys to ridge-top forests. Likely, it was introduced as a botanical specimen at the Ho’omula botanical garden. The first adventive seedlings were found growing in a disturbed area just outside the grounds.
It makes more than 1000 viable seeds per meter square per plant! Attracted to the red seeds, nonnative birds eat and disperse them around. As is the case with lantana, nonnative birds are spreading invasive plants.
The Division of Forestry and Wildlife of the Hawaiʻi Department of Land and Natural Resources has designated this species as one of “Hawaiʻi’s Most Invasive Horticultural Plants.”
Description and Dispersal:
- A multi-branched shrub growing up to 25 feet
- Bright green leaves are oppositely arranged
- Prominent winged petiole
- Yellow flowers have 5 petals with white stamens
- Flowers are loosely arranged in clusters
- Starshaped fruit capsules open to reveal numerous scarlet arils
- Seeds are spread by non-native birds
High Risk Traits:
- Thrives in tropical climates
- Naturalized on Oahu, Hawaiian Islands, Sri Lanka, Java, Jamaica
- A pioneer species capable of invading disturbed habitats
- An environmental weed of Sri Lanka and the Seychelles
- Alternate host for oil palm nettle caterpillar
- A light demanding pioneer species capable of establishing in shade
- Tolerates many soil types
- Forms dense thickets
- Reproduces by seed and vegetatively by adventitious roots
- Capable of reaching maturity in 3-4 years
- Seeds dispersed by birds, possibly by water and intentionally by people
- Prolific seed production
- Able to coppice and resprout after cutting
Low Risk Traits:
- Unarmed (no spines, thorns or burrs)
- Palatable to animals
- Non-toxic
- Ornamental and medicinal uses
- Seeds lack dormancy and may not form a long-lived seed bank
- Herbicides may provide effective control
