Survival secrets of the desert moss


When we think of survival strategies of plants in the desert, what comes to mind is a cactus with its succulent leaves, thorns, and deep roots. However, the desert moss Syntrichia caninervis Mitt. (Pottiaceae) has a unique adaptation which has enabled it to thrive in extreme environments.

S. caninervis is one of the most common desert mosses and is widely distributed. It lacks true roots with vascular bundles, and relies on above-ground structures for water collection, transport and storage. The 3-8 mm desert moss has about 20 leaves, and each leaf has a semi-transparent fibre or ‘leaf hair point’ called awn, growing out from its distal terminus. These awns are specialized to collect water efficiently from limited precipitation events including dew, fog, mist or even rain. These specialized structures help the desert moss to rehydrate itself and turn green within seconds following precipitation.

Syntrichia caninervis

The team used high speed imaging and environmental scanning electron microscope (ESEM) to reveal direct relationship between water harvesting system and structural features of the desert moss. They have hypothesized four methods of water capture and transport: nucleation of water droplets and films on the leaf hair from humid atmospheres; collection of fog droplets on leaf hairs; collection of splash water from rain droplets; and transportation of the acquired water to the leaf itself.

The study gives scientific backing to the previously speculated function of awns in S. caninervis. It demonstrates how bryophytes efficiently utilize coupled multi-scaled structures to collect water from limited sources. The team hopes that water scarcity in some regions can be overcome by the design and development of more efficient water harvesting systems based on the moss awn design.

The article is based on the research paper “The upside-down water collection system of Syntrichia caninervis published in Nature Plants. Image is taken from the “Wild about Utah” website.