Family: Cactaceae

Origin, Description & Uses:
Opuntia galapageia var. myriacantha, commonly known as tree prickly-pear or cacto gigante, is a distinctive cactus native to the Galápagos Islands. Unlike many low-growing prickly-pears, this variety can develop a tall, trunk-like form resembling a small tree, with broad, flattened green pads covered in clusters of spines. It produces colorful flowers followed by fleshy fruits that are eaten by wildlife and, in some regions, by people. In its native habitat, it plays an important ecological role by providing food and shelter for birds and reptiles. Because of its unusual appearance and drought tolerance, it is sometimes cultivated as an ornamental plant in arid and tropical landscapes.

Risks & Threats:
Although Opuntia galapageia var. myriacantha is not known to be naturalized in Hawaii, it possesses traits that are cause for concern. Like other prickly-pears, it is adapted to dry environments, can tolerate harsh growing conditions, and may spread through seeds or detached plant segments. Dense, spiny growth could potentially displace native vegetation, restrict access for people and animals, and create difficult-to-manage infestations if it escaped cultivation. Spines can also pose hazards to pets, livestock, and wildlife. Because some Opuntia species have become invasive in tropical and subtropical regions worldwide, caution is recommended to ensure that this variety will not negatively impact Hawaii. Ongoing evaluation and responsible cultivation practices are advised.

High Risk Traits:

• Grows in tropical climates
  
• Other Opuntia species are invasive
  
• Forms dense thickets in native range
  
• Reproduces by seeds and vegetatively by fallen trunks and cladodes
  
• Seeds dispersed by birds and other frugivorous animals
  
• Limited ecological information may reduce accuracy of risk prediction

Low Risk Traits:

• No reports of invasiveness or naturalization, but no evidence of widespread introduction outside native range
  
• Spiny
  
• Seedlings palatable
  
• Non-toxic
  
• Reportedly self-incompatible