Family: Rosaceae
Rubus rosifolius (thimbleberry) is a fast-growing, woody shrub in the rose family, native to tropical and subtropical regions of Asia and the Pacific. It produces bright red, edible berries that resemble small raspberries and has pinnately compound leaves with 7 leaflets—sometimes only 5 in the upper leaves—featuring toothed margins and a slightly hairy underside. The plant forms dense thickets that can outcompete native vegetation and degrade habitat quality, particularly along forest edges, roadsides, and other disturbed areas. Its ability to grow in a wide range of soil types and elevations, along with prolific seed production dispersed by birds, makes it a highly invasive species in Hawai‘i.
Thimbleberry is now naturalized across all the main Hawaiian Islands, including Kaua‘i, O‘ahu, Moloka‘i, Lana‘i, Maui, and Hawai‘i. Gardeners and land managers are strongly encouraged to avoid planting this species due to its aggressive spread and potential impacts on native ecosystems. Control methods, such as hand-pulling young plants or carefully applying herbicide to larger thickets, are recommended to slow its invasion.
High Risk Traits:
- Climate Versatile: Thrives in tropical/subtropical climates and a wide range of elevations and soils.
- Proven Invader: Naturalized and invasive outside its native range, forming dense thickets in forests.
- Weedy Relatives: Other species in the Rubus genus are invasive.
- Physical Nuisance: Has spines, a climbing habit, and forms dense, impenetrable thickets.
- High Reproductive Output: Produces abundant, viable seeds and can spread via vegetative suckers.
- Effective Dispersal: Seeds are bird-dispersed and survive gut passage; also spread by people for its uses.
Low Risk Traits:
- Not Toxic: Non-toxic to humans and animals; palatable to livestock.
- Pollination Dependent: Relies on insect pollinators and is not self-fertile.
- Controllable: Can be managed with herbicides and grazing.
