Super-sized: Giant taro

This extraordinary plant is a staple food for over three hundred million people worldwide. Just like our potato, the corm (a swollen stem) is peeled and boiled, and eaten as an important source of carbohydrate.

The giant taro leaves and stems are also eaten as a vegetable rich in vitamins. In the raw state, the giant taro is poisonous to humans until prolonged boiling removes the toxin calcium oxalate, also found in other aroids).

Largest leaf in the world

Giant taros have the largest un-split leaf in the world, potentially reaching 3.4m (10’) across. The giant leaves are ideally adapted to absorbing the small amount of light that reaches the rainforest floor under the dense tree canopy. The leaves are supported by thick stalks over 10cm (4’’) wide and up to 2m (6’) long.

Protection against the elements

The large leaves of giant taro may be broken by heavy tropical rain, but it has cleverly adapted to help solve this problem.

All over the leaf surface are tiny bumps coated with wax. The bumps are only five to ten thousandths of a millimetre high, but enough to reduce the surface contact of water droplets and let them roll off the leaf as if beads. A rolling droplet also gathers dirt, cleaning the leaf.

In unsuitable growing conditions, the giant taro can become dormant, indicated by each new leaf getting progressively smaller. When conditions improve, such as light, temperature, and soil moisture, then the plant can regenerate from a tiny piece of corm, as with a potato tuber (or perennial weed root in the garden!).