Pandanus

Lore & Background

Pandanus species vary from small shrubs under 1 meter to trees 20 meters tall, with stout trunks ringed with leaf scars and often thick stilt roots for support. They are dioecious, with male flowers 2–3 cm long and fragrant, and female flowers producing round, bract-surrounded fruits. The fruit is a multiple drupe, 10–20 cm in diameter, changing from green to bright orange or red as it matures, and can remain on the tree for over 12 months. Leaves are strap-shaped, 30 cm to 2 m long, and may be spiny. The oldest credible fossil is Pandanus estellae from Queensland, Australia, dating to the Oligocene around 32–28 million years ago. Phylogenetic analyses of maternal DNA divide the genus into two large clades (I and II), each further split into two subclades, with the split between clades occurring in the early Miocene. Nuclear genomics reveals reticulate evolution and transoceanic adaptive introgression across the Indian Ocean, with a key lineage (Clade Ba) acting as a genetic bridge between Asian and Afro-Malagasy populations. Swamp lineages show convergent evolution driven by similar climatic pressures, not hybrid origin.

Reader's Guide

Pandanus is a significant Paleotropical genus, with the greatest number of species in Madagascar and Malaysia. It grows from sea level to 3,300 meters, thriving in littoral habitats, withstanding drought, strong winds, and salt spray. The genus is named from the Malay word pandan, derived from Proto-Austronesian *paŋudaN, reflecting its deep cultural importance across Austronesian cultures. Traditionally divided into six subgenera, molecular analyses show these are not evolutionarily accurate, as all but Coronata are polyphyletic or paraphyletic. Ecologically, Pandanus fruits are eaten by bats, rats, crabs, and elephants, but most species are dispersed primarily by water, allowing spread to other islands. Climate and soil analyses link the largest split (Clades I and II) to differences in seasonal temperature, precipitation, and soil drainage, with Clade II species possessing hydrenchyma (water storage tissue) aiding adaptation to water-stressed environments. Nuclear evidence shows this hydrenchyma fixation was facilitated by chloroplast capture and adaptive introgression coinciding with Miocene forest contractions and intensifying seasonality after the Tethys Sea closure. Uses include handicrafts from leaves, such as mats and ropes, and culinary use of Pandanus amaryllifolius leaves in Southeast Asian and South Asian cuisines, often called the 'vanilla of Asia.' In Hawaiʻi, dry leaves (lauhala) are used for weaving. The genus's evolutionary history and ecological adaptations underscore its role in tropical and subtropical ecosystems.

Did You Know?

• The oldest credible fossil of Pandanus is Pandanus estellae, a silicified fruit from Queensland, Australia, dating to the Oligocene around 32–28 million years ago.
• Pandanus fruits can stay on the tree for more than 12 months and change from green to bright orange or red as they mature.
• The genus name is derived from Proto-Austronesian *paŋudaN, with cognates in many Austronesian languages including Hawaiian hala and Malagasy fandrana.
• Nuclear phylogenomic evidence shows that the ecological fixation of hydrenchyma in Clade II Pandanus was facilitated by chloroplast capture and adaptive introgression events.