# Hydro-Responsive Curling of the Resurrection Plant Selaginella lepidophylla

## TL;DR

This study explores how Selaginella lepidophylla, an ancient resurrection plant, exhibits distinct dehydration-triggered curling behaviors in its stems, enabling rapid shape change and environmental adaptation.

## Contribution

It reveals the differential conformational changes in outer and inner stems during dehydration, advancing understanding of plant hydro-responsiveness and inspiring deployable structure design.

## Key findings

- Outer stems curl into rings quickly upon dehydration.
- Inner stems curl into spirals gradually due to strain gradients.
- The plant's structure facilitates rapid opening upon rehydration.

## Abstract

The spirally arranged stems of the spikemoss Selaginella lepidophylla, an ancient resurrection plant, compactly curl into a nest-ball shape upon dehydration. Due to its spiral phyllotaxy, older outer stems on the plant interlace and envelope the younger inner stems forming the plant centre. Stem curling is a morphological mechanism that limits photoinhibitory and thermal damages the plant might experience in arid environments. Here, we investigate the distinct conformational changes of outer and inner stems of S. lepidophylla triggered by dehydration. Outer stems bend into circular rings in a relatively short period of desiccation, whereas inner stems curl slowly into spirals due to hydro-actuated strain gradient along their length. This arrangement eases both the tight packing of the plant during desiccation and its fast opening upon rehydration. The insights gained from this work shed light on the hydro-responsive movements in plants and might contribute to the development of deployable structures with remarkable shape transformations in response to environmental stimuli.