Opiuma is an invasive tree native to North, Central, and South America, from California down through Mexico to Venezuela. Portuguese traders brought seeds to the Philippines sometime between 1521 and 1815. From there, seeds were introduced throughout the tropics. Finally, it was introduced to Hawaii in 1870 as a shade tree for the dry lowland areas. Eight hundred trees were intentionally planted in forest reserves on Oahu and Kauai in 1952. Interestingly, only two years later, the 1954 book ‘Noxious Weeds of Hawaii’s Ranges’ lists Opiuma as problematic. Today it is naturalized on all the main Hawaiian Islands.
It invades dry areas, withstanding heat and drought. Pastures and rangelands are especially susceptible to invasion. The self-seeding tree creates impenetrable thorny thickets. It resprouts after fires and cutting and vigorously produces root suckers. Management is difficult without herbicide use. Attracted to the red seed pods, Introduced birds, such as the false myna, aid in seed dispersal and increased naturalization.
The common name Manilla Tamarind pays homage to its first intentional introduction. Opiuma is the local name in Hawaii. The genus name ‘Pithecellobium’ is Greek for pithekos (ape or monkey) and ellobion (earring). The species name ‘dulce’ is a reference to the sweet taste of the seed pods.
Description and Dispersal:
- A multi-stemmed tree with an irregular crown
- Four green leaflets form a compound leaf
- Greenish-white flowers are somewhat spherical and grow in clusters
- Seed pods coil into a distinctive shape turning pink when ripe.