Family: Bromeliaceae

Tillandsia polystachia, commonly known as air plant, is a species of epiphytic bromeliad. Epiphytic plants are those that grow attached to other plants or objects without deriving nutrients from them. It is native to the forests of Central and South America. It typically grows on tree branches or rocks, using its roots primarily for anchorage rather than nutrient absorption. This species has been cultivated as an ornamental in the Hawaiian Islands and spreads by wind-dispersed seeds. On the islands of Oahu and Hawaii, it is reported to form dense cover on branches and trunks of supporting trees in landscaping, possibly depriving them of light. Similar negative impacts could presumably occur if it became established on economically important trees or trees in native ecosystems.

Tillandsia polystachia is particularly bad in the Hilo and Keaau regions of Hawaii Island. Locally it has earned the name ‘Sky Weed.’ It completely blankets certain trees and palms. Some are growing directly on the utility lines. While it is easy to grab some, do NOT take this home. It will smother your trees, your neighbor’s trees, and other places. The only way to get rid of them is by physically pulling them off.

Like many invasive species, Tillandsia polystachia is well-behaved in other parts of the world, only to escape cultivation and run amuck in Hawaii. There are few to no reports of invasiveness worldwide.

Description and Dispersal:

• Epiphytic herb
  
• Narrowly triangular, usually flat leaves in a dense, spreading rosette
  
• Leaves usually yellow-green, flushing red when exposed to the sun
  
• Inflorescence is 30 cm long and can be pinnately or subdigitately compound
  
• Fruit is a capsule containing many small, wind-dispersed seeds

High Risk Traits:

• Tillandsia polystachia, commonly known as air plant, is a species of epiphytic bromeliad. Epiphytic plants are those that grow attached to other plants or objects without deriving nutrients from them. It is native to the forests of Central and South America. It typically grows on tree branches or rocks, using its roots primarily for anchorage rather than nutrient absorption. This species has been cultivated as an ornamental in the Hawaiian Islands, and spreads by wind-dispersed seeds. On the islands of Oahu and Hawaii, it is reported to form dense cover on branches and trunks of supporting trees in landscaping, possibly depriving them of light. Similar negative impacts could presumably occur if it became established on economically important trees or trees in native ecosystems.
  
• Broad elevation range in tropical environments
  
• Naturalized on Kauai, Oahu, and Hawaii (Hawaiian Islands
  
• A landscaping weed, established on and negatively impacting landscaping trees
  
• A potential agricultural and environmental weed with the ability to establish on and deprive trees of light and possibly other nutrients
  
• Other Tillandsia species are invasive weeds
  
• Shade-tolerant
  
• Smothering habit, forming dense growth on branches and trunks that may impede photosynthesis
  
• Reproduces by wind-dispersed seeds
  
• Hybridizes with other species
  
• Self-fertile
  
• Seeds dispersed by wind and through intentional cultivation

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Non-toxic
  
• Herbicides used to control other invasive Tillandsia species may be effective