A fern that rises from the dead

Tree ferns are an ancient group of plants, believed to have evolved much earlier than dinosaurs.

Flowering plants were just entering the scene when giant dinosaurs roamed the earth. Back then, ferns — plants that produce no flowers or seeds but reproduce by spores — dominated our planet’s plant life. These plants are slow growers and thrive in nutrient-poor soils and marshes, exhibiting one of the strangest adaptations in the plant world. 

A serendipitous discovery has revealed that one such adaptation repurposes their dead leaves or fronds into roots. In 2019, scientists from the University of Illinois were scouring the forest floor of Quebrada Chorro woodlands in Panama to understand how the roots of coniferous trees absorb nutrients. A dense bush of Cyathea rojasiana — a tree fern species that grows up to two metres tall, discovered in the early 2000s — caught their attention instead. When they tried to remove the drooping, seemingly dead leaves, they were astounded to find a dense network of tiny rootlets growing from the other end of the leaves. 

Further laboratory experiments revealed that the ‘dead’ fronds were surprisingly drawing nitrogen from the forest’s nutrient-poor and water-logged soil and supplying it to the plant. Interestingly, even after the fronds became roots, they still looked wilted, deceiving other scientists who may have come across these ferns. 

The discovery makes Cyathea rojasiana the only plant known to revive its dead leaves and repurpose them into roots. This intelligent adaptation for a slow-growing fern, which would otherwise have to invest heavily in growing new fronds and roots, is a testament to nature’s evolutionary tale.

- Spoorthy Raman