A woody vine-like plant, it aggressively smothers everything in its path, creating impenetrable thickets.
Endemic plant to Madagascar, both species rubber vine looks similar to purple Alamanda. A prominent midvein on the leaves is an excellent way to distinguish rubber vine from purple Alamanda.
Rubber vine was brought into cultivation in the early 1900s for industrial uses. It was thought that rubber could be made from the sap it exudes, hence the common name. Nowadays, it is cultivated for its ornamental purple flowers.
It is considered a weed of National Significance in Australia where the invasion costs the cattle industry 18 million a year, not including extra costs for fencing.
Both species have naturalized on Oahu, Maui, and Hawaiʻi Island. Invasions occur on the dry sides of the island chain.
The Division of Forestry and Wildlife of the Hawaiʻi Department of Land and Natural Resources has designated these species as one of “Hawaiʻi’s Most Invasive Horticultural Plants.”
Description and Dispersal:
- Woody shrubs 6-9 ft tall if self-supported, but will climb up to 30 ft high
- Shiny, dark green leaves 3 in long with a prominent midvein
- Flower petals join in a funnel at the base and are white, pink, or purple; triangular seedpods (4 - 6 in long) grow in wing-like pairs
- Present in landscaped areas on Kaua'i, O'ahu, and Big Island, larger infestations on Maui and Moloka'i
- Each seedpod contains 380-840 seeds, silky hairs on the seeds allow them to spread by wind and water; seeds are also known to float and survive for a month in salt water and still be viable