Family: Apocynaceae
Calotropis gigantea, commonly known as crown flower, crownplant, or giant milkweed, is a large shrub or small tree native to South and Southeast Asia. It is easily recognized by its thick, gray-green leaves and clusters of waxy, star-shaped flowers, most commonly lavender-purple but also occurring in white forms. In Hawaiʻi, crown flower is especially well known as a traditional lei flower associated with aliʻi and cultural celebrations. Both color forms have become popular garden plants due to their drought tolerance, year-round flowering, and ability to thrive in warm, coastal, and lowland environments.
Although crown flower is now naturalized in Hawaiʻi and considered high risk due to its ability to spread beyond cultivation, it continues to be widely grown for cultural, ornamental, and practical uses. The plant produces abundant wind-dispersed seeds and can establish in dry, disturbed, or coastal habitats, where it may outcompete native vegetation. Rather than discouraging planting altogether, responsible cultivation is encouraged: gardeners should monitor plants for unwanted seedlings, remove seed pods before they open, and avoid planting near natural areas. With proper management, cultivated crown flower can be enjoyed while reducing the risk of further spread into areas where it may be unwanted.
High Risk Traits:
- Thrives in tropical climates
- Naturalized on Kauai, Oahu, Molokai, Maui (Hawaiian Islands) and several locations worldwide
- A disturbance-adapted weed with potential impacts to agriculture and natural areas
- Calotropis procera is an invasive weed
- Unpalatable to browsing and grazing mammals
- Toxic to animals and people
- Tolerates many soil types
- Reproduces by seeds (rarely in Hawaii) and vegetatively by suckering
- Able to reach maturity in <1 year
- Seeds, when produced, dispersed by wind, water and intentionally by people
- Tolerates hard pruning
Low Risk Traits:
- Unarmed (no spines, thorns, or burrs)
- Thrives in full sun and high light environments
- Ornamental and host plant of monarch butterflies
- Limited or absent seed set in Hawaiian Islands reduces risk of inadvertent dispersal or spread
- Herbicides may provide effective control
