Mona Cromb of Green Island asks :-

We have an unusual plant in our garden which curls up when dry and opens when wet. Reputedly it was brought back from Egypt by an uncle there for the First World War. He called it a Desert Rose. What is it?

Paul Broady, a botanist at the University of Canterbury, responded.

Going by your photographs, the description of your specimen and "The New Royal Horticultural Society Dictionary of Gardening", it seems that the plant is Selaginella lepidophylla. Common names which have been attached to this include Resurrection Plant, Resurrection Fern and Rose-of-Jericho.

It is a native of the americas, being found in Texas and Arizona and south to Peru. The brief description in the Dictionary states that the leaves become tinged a rust colour with age. It also refers to the stems being curled up in a ball when dry but expanding and resuming a fresh appearance when soaked in water. It notes that the plant is often sold as a curiosity for this reason.

I imagine that this behaviour is an adaptation for survival in arid and semi-arid regions. The curled stage might help conserve residual moisture within the plant and then when moisture becomes more readily available the plant briefly opens out to capture sunlight.

Selaginella is a member of the spore-forming vascular plants in the division Lycophyta. Such plants do not form seeds but disperse themselves with microscopic single-cell spores. More familiar examples of related plants would be ferns. One of the common names is confusing in this respect as Selaginella is not a fern but in a related division. Ancient lycophytes formed massive forest trees during the Carboniferous Period some 300 million years ago. A few species of small lycophytes are all that remain on present day Earth.