Family: Myrtaceae
Corymbia citriodora (lemon-scented gum) is a tall, evergreen tree native to eastern Australia that’s easily recognized by its smooth, pale bark and long, narrow leaves that give off a strong, fresh lemon scent when crushed. It can grow up to 40–50 m tall, forming a graceful, straight trunk and a light, open canopy. People value lemon-scented gum for ornamental planting in parks, landscapes, and large gardens because of its attractive form and fragrant foliage. Its essential oils are also used in cleaning products, perfumes, and aromatherapy for their uplifting citrus-like aroma. On some Hawaiian islands, this species has established beyond cultivation: it’s considered naturalized on Moloka‘i and is observed as potentially naturalizing on Maui, meaning it’s beginning to spread on its own in the landscape.
While lemon-scented gum can add beauty and fragrance to planted areas, it can pose ecological concerns when it escapes cultivation. In areas where it naturalizes, it can compete with native vegetation for light, water, and nutrients, potentially altering habitat structure and fire regimes. Its leaf litter and oils are also highly flammable, which may increase wildfire risk in dry environments. Because of these traits, land managers and gardeners in Hawai‘i should be aware of its potential to spread and consider using native or well-behaved alternative species, especially near natural areas where protection of native ecosystems is a priority.
High Risk Traits:
- Broad climate suitability
- Naturalized in Australia (outside native range), Hawaii, California
- Environmental Weed of Australia
- Potentially allelopathic
- Alternate host of Puccinia psidii
- Tolerates many soil conditions (and potentially able to exploit many
- different habitat types)
- Hybridizes with other Corymbia species
- Pods dispersed whole by wind
- Self-compatible
- Prolific seed production
- Tolerates fire, and can coppice
Low Risk Traits:
- Non-toxic
- Non-spiny
- Ornamental value
- Timber tree
- Intolerant of shade
