Family: Apocynaceae

Origin, Description & Uses
Strophanthus preussii is a climbing shrub or woody vine native to a broad region of tropical Africa, ranging from West Tropical Africa to Tanzania and Angola. It typically grows in forest margins, woodland edges, and other warm, humid habitats where it can climb over surrounding vegetation. The species is noted for its distinctive and often intricate flowers, as well as its elongated seed pods. Like other members of the genus, it contains biologically active compounds, including cardiac glycosides, which have historically been associated with traditional medicinal use and, in some regions, the preparation of arrow poisons. It is also occasionally cultivated as an ornamental plant in botanical collections due to its unusual floral structures and climbing habit.

Risks & Threats
There are currently no strong indications that this species is naturalized or invasive in Hawaiʻi. However, caution is warranted because plants in this genus can be toxic if ingested, particularly the seeds and sap, posing potential risks to people, pets, and livestock. In suitable tropical environments, its climbing growth form could allow it to overtop and smother nearby vegetation if it were to escape cultivation. While overall risk appears low at present, ongoing evaluation is appropriate given its toxicity and the ecological behavior of related species in the genus.

High Risk Traits:

• Native to tropical Africa and already introduced to Japan, Florida, and the UK
  
• Toxic to animals and humans, with poisonous milky sap
  
• Shade-tolerant climbing liana that can smother other vegetation
  
• Reproduces by viable seed with a short generation time of one year
  
• Seeds adapted for wind dispersal and intentionally spread as an ornamental
  
• Produces numerous seeds per follicle

Low Risk Traits:

• No evidence of naturalization, or weedy behavior anywhere
  
• Not known as a pest, pathogen host, or environmental weed
  
• Lacks physical defenses like spines, burrs, or allelopathic chemicals
  
• Does not form dense thickets, spread vegetatively, or create fire hazards
  
• No evidence of dispersal by water, animals, or as a contaminant
  
• No persistent seed bank or tolerance to mutilation/fire reported