Family: Malvaceae

Origin, Description & Uses:
Hibiscus syriacus, commonly known as rose of Sharon, is a deciduous flowering shrub or small tree native to south-central and southeastern China, as well as Taiwan. It typically grows 8–12 feet tall and is valued for its showy, hibiscus-like flowers that bloom in shades of white, pink, purple, and blue, often with contrasting centers. Blooming in late summer when many other plants have finished flowering, it is widely used as an ornamental in gardens, hedges, and landscapes. Rose of Sharon is appreciated for its tolerance of a range of soil types and urban conditions, as well as its ability to attract pollinators such as bees and butterflies.

Risks & Threats:
Although not known to be naturalized in Hawaiʻi, rose of Sharon does possess traits that are cause for concern. It produces abundant seeds and can spread beyond intended planting areas in suitable climates. In other regions, it has demonstrated the ability to establish in disturbed habitats, where it may compete with native vegetation. Its adaptability to a wide range of environmental conditions further increases its potential risk. While it is not currently considered invasive in Hawaiʻi, further evaluation is needed to determine if it could impact the state. Caution is recommended when planting, and gardeners should monitor for unwanted spread to ensure it does not negatively affect local ecosystems.

High Risk Traits:

• Naturalized in temperate regions of the US (e.g., Arkansas, Tennessee, Georgia)
  
• Listed as a minor exotic pest plant in Georgia
  
• Tolerates a wide range of soils and conditions (drought, compaction, pollution)
  
• Shade tolerant
  
• Self-fertile (capable of self-pollination)
  
• Reproduces by seed and vegetative fragmentation (suckering)
  
• Prolific seed production (anecdotal)
  
• Seeds form a persistent soil seed bank (orthodox storage behavior)
  
• Difficult to remove once established (deep taproot)
  
• Host for pests and pathogens (aphids, Japanese beetles)
  
• Unpalatable to deer and other mammals

Low Risk Traits:

• No evidence of toxicity to animals or humans
  
• No spines, thorns, or burrs
  
• Does not form dense thickets or create fire hazard
  
• Primarily disperses seeds by gravity (limited long-distance dispersal)
  
• Not bird-dispersed (dry capsule, not fleshy fruit)
  
• Sterile cultivars exist (reduces risk in horticultural use)
  
• Controllable with herbicides (e.g., glyphosate)