Swiss cheese plants' iconic leaves help them to avoid stress, according to a US scientist.

一位美国科学家发现，蓬莱蕉的标志性叶子能帮助它们远离压力。

The "monster" leaves can reach up to 90cm long

Their familiar hole-riddled leaves allow the plants to capture sunlight more regularly, his research suggests.

The counterintuitive（违反直觉的） idea explains how such plants can survive in shady rainforests. 

Commonly grown as house plants, they are found in the wild from southern Mexico to Colombia.

Many theories have been suggested for the unusual perforated（穿孔的） leaves.

One is that the holes in the leaves allow the plants to resist hurricane winds, by letting the wind pass through. Another that they allow better temperature regulation or water to run through the plants down to its roots. Some have suggested the holes somehow camouflage（伪装，掩饰） the plants, hiding them from herbivores.

But these ideas have rarely been scientifically tested.

Now research by graduate student Christopher Muir at the University of Indiana, in Bloomington, US, suggests the holes are an adaptation to the plants' rainforest habitat.

His findings are published in the journal The American Naturalist.

Leaves compared

The Swiss cheese plant Monstera deliciosa lives in the dark understory of tropical rainforests. It relies on capturing unpredictable shafts on sunlight, known as "sunflecks", in order to photosynthesise for energy.

Mr Muir questioned whether the sunflecks could explain the unusual leaf shapes so he used mathematical models to compare leaves with and without holes.

He found that both leaf shapes benefit equally from the same amount of sunlight.

Although a leaf with holes will miss some sunlight, because it filters through the holes, solid leaves with the same surface area actually take up less space, so their access to sunlight is restricted.

Mr Muir's models revealed that a leaf with the same surface area, but riddled with holes, would contact sunlight more regularly because it takes up more space.