Programmes

Chinese Aquilaria’s Ingenious Strategy for Seed Dispersal

Do the seeds of this Aquilaria tree remind you of anything?

  

Unopened seed capsules of Aquilaria sinensis (left). An opened capsule reveals two seeds that drop down on thread-like appendages and remain dangling in the air for up to one week (right). Photo credits: Jin Gang

 

The seeds of Aquilaria sinensis look surprisingly like a caterpillar dangling on a length of silk from a twig. There is an interesting evolutionary story behind this remarkable mimicry.

The appearance of these dangling seeds attracts wasps that normally feed on caterpillars. A fleshy store of lipids and proteins situated immediately above each seed completes the illusion, and the deceived wasp begins to attack the ‘caterpillar’. In so doing, the wasp is able to sever the silk-like thread and carry the seed off for consumption―although a tough seed coat prevents them from destroying the seed completely. In one study in Guangdong (Chen et al., 2016), wasps were found to transport intact seeds over 80m away from mother trees. Aquilaria sinensis thereby exploits the feeding response of wasps to achieve seed dispersal, allowing for a far more scattered distribution of seedlings throughout the forest than could be achieved by gravity alone.

 

Reference

Chen, G., Liu, C., & Sun, W. (2006) Pollination and seed dispersal of Aquilaria sinensis (Lour.) Gilg (Tymelaeaceae): An economic plant species with extremely small populations in China. Plant Diversity. 38, pg 227-232.