Family: Asteraceae

Origin, Description & Uses
Youngia japonica, commonly known as Oriental hawksbeard or Oriental false hawksbeard, is a small annual herb native to East Asia, including Japan, China, and Korea. It belongs to the daisy family (Asteraceae) and typically grows as a low rosette of soft, lobed leaves that produce slender stems topped with small yellow dandelion-like flowers. The plant thrives in disturbed areas such as roadsides, lawns, gardens, and agricultural fields. In parts of its native range, it has been used as a minor leafy vegetable or forage plant, and it is sometimes noted for its ability to grow quickly in poor soils. In Hawai‘i, it has become naturalized and is found on Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Maui, and Hawai‘i Island.

Risks & Threats
Although Youngia japonica may appear harmless, it is naturalized in Hawai‘i and possesses traits that raise concern for tropical island ecosystems. The species produces abundant wind-dispersed seeds and can quickly colonize open or disturbed habitats, allowing it to spread rapidly across landscapes. This ability could enable it to compete with other vegetation and establish persistent populations in fields, roadsides, and other managed areas. Because it is already widespread across the Hawaiian Islands and capable of spreading easily, it could detrimentally impact native plant communities and ecological processes. For these reasons, it is considered a high-risk species, and gardeners and land managers are encouraged to choose non-invasive or native alternatives when selecting plants.

High Risk Traits:

• Broad climate and elevation range, demonstrating environmental versatility
  
• Grows in temperate to tropical climates
  
• Naturalized on main Hawaiian Islands (except Ni'ihau and Kaho'olawe) and widely naturalized elsewhere
  
• A disturbance-adapted weed of lawns, gardens, and cultivated areas that can also invade native ecosystems and threaten endangered plant species (Hawaiian Islands)
  
• Shade-tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds
  
• Autogamous (able to produce seeds through self-fertilization)
  
• An annual, reaching maturity in <1 year
  
• Seeds dispersed by wind, water & unintentionally by people
  
• Prolific seed production (but probably not in excess of 1000 m-2)
  
• Forms a persistent seed bank (up to 20 years or more)
  
• Mechanical control may be difficult due to growth habit

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Provides fodder for livestock
  
• Not reported to spread vegetatively
  
• Herbicides may provide effective control