Selaginella lepidophylla (syn. Lycopodium lepidophyllum) is a species of desert plant in the spikemoss family (Selaginellaceae). Known as a “resurrection plant”, S. lepidophylla is renowned for its ability to survive almost complete desiccation. During dry weather in its native habitat, its stems curl into a tight ball, uncurling only when exposed to moisture.
The outer stems of the plant bend into circular rings after a relatively short period without water. The inner stems instead curl slowly into spirals in response to desiccation, due to the action of the strain gradient along their length. Selaginella lepidophylla reaches a maximum height of 5 cm, and is native to the Chihuahuan Desert.
Common names for this plant include flower of stone, false rose of Jericho, rose of Jericho, resurrection plant, resurrection moss, dinosaur plant, siempre viva, stone flower, and doradilla.
Selaginella lepidophylla is not to be confused with Anastatica hierochuntica a flowering plant in the mustard family, Brassicaceae, known as the true Rose of Jericho. Selaginella lepidophylla is a true resurrection plant that can revive and regain metabolic function after a period of extreme desiccation. Anastatica hierochuntica is not a resurrection plant, but rather a tumbleweed capable of repeated hygroscopic expansion and retraction, which superficially resembles revival.
The striking feature of Selaginella lepidophylla is its adaptation to conditions of prolonged drought in its natural environment. It deploys the physiological strategy of drying up and rolling inwards in the absence of water to form a ball, and can survive for up to several years, and lose up to 95% of its moisture content, without suffering damage.
When ground and air humidity begin to rise again, even a considerable time after it has wilted, the plant “resuscitates”. If rehydrated, it continues its life cycle, fully recovering its photosynthesis and growth abilities. When desiccated, its rooted leaves become leathery at the base, appearing dark brown or light to reddish brown.
The dry ball opens a few hours after being placed in contact with water, the parched leaves gradually resuming their green colour. If the roots are not too damaged, the plant may survive in pozzolanic ash. No matter how dried or damaged it becomes, because of the particular biological structure of its leaves the plant retains the ability to imbibe water and unfold itself, even many years after its death.
The plant enters a dormant state in the absence of water, avoiding tissue and cell damage during drying by synthesizing trehalose, a crystallized sugar that acts as a compatible solute. Dissolved salts become concentrated in the plant tissues as water evaporates. The trehalose produced by the plant acts in place of the evaporating water, so preventing the salts from causing damage and protecting against death due to an excess of salinity. S. lepidophylla also uses betaines, substances which have the same function as trehalose.
Once water is restored to the plant tissues, the sugar crystals dissolve and the plant’s metabolism, until then paralyzed, reactivates. Leaves that seemed dead turn green, and open.
Adapted to the desert environment, Selaginella lepidophylla can survive without water for several years, drying up until it retains only 3% of its mass. The plant can live and reproduce in arid regions for long periods of time. When living conditions become too difficult, the plant’s survival mechanism allows it to dry out gradually. Its leaves turn brown and fold in, giving the plant the appearance of a ball. In dormancy, all of its metabolic functions are reduced to a minimum.
Where drought persists, the roots may detach, allowing the plant to be carried by the wind. If it encounters moisture, Selaginella lepidophylla may rehydrate and take root in the new location.
Plants that go through the resurrection process are not always able to “rise again”. If dehydration has been too rapid, or in the event of irregular alternation of drought and wet conditions, the plant has insufficient time to prepare properly to resist the water stress to which it is subjected. Likewise, the ability to dry up and rehydrate may diminish, in which case, after dozens of cycles of alternate desiccation and regrowth, the plant dies.
As a sporophyte, S. lepidophylla does not produce flowers or seeds but reproduces through spores. Selaginella are neither aquatic plants nor epiphytic plants.
Selaginella lepidophylla is sold as a novelty item, as bare root stock in its dry state, in which it may be revived with only a little water.
The plant’s ability to survive extreme desiccation was noted by Spanish missionaries when they reached the New World, including the area that was to become the United States. The missionaries used S. lepidophylla to demonstrate to potential native converts the concept of being reborn. Because of its properties, the false rose of Jericho was considered a lucky charm, and was passed on in families from generation to generation.
Selaginella lepidophylla has been used as a herbal medicine. An infusion is made by steeping a tablespoon of dried material in hot water, and the resulting tea is used to treat colds and sore throat.
In Mexico, S. lepidophylla is sold as a diuretic. Women drink the water in which the plant is soaked to facilitate childbirth. The speed at which the plant blossoms in the water is interpreted as an indication of whether the delivery will be easy or difficult.
The plant is also used in the rites of voodoo and Cuban santería to invoke love and fortune. The plant is said to absorb “negative energy” when worn on the body.
Anastatica is a monotypic genus of plants in the family Brassicaceae containing the single species Anastatica hierochuntica. The plant is a small gray annual herb that rarely grows above 15 centimetres (6 in) high, and bears minute white flowers. It is a tumbleweed capable of hygroscopic expansion and retraction. However, it is not a true resurrection plant, because the plant’s dead tissues do not revive and turn green.
This species is not to be confused with Selaginella lepidophylla, also sometimes referred to as “rose of Jericho”, or “false rose of Jericho”, which is a true resurrection plant that can revive from a dried state and regain the processes of respiration and photosynthesis.
Common names include Maryam’s flower, flower of St Mary, St. Mary’s flower, Mary’s flower, white mustard flower , and rose of Jericho.
Anastatica is found in arid areas in the Middle East and the Sahara Desert, including parts of North Africa and regions of Iran, Egypt, Israel, Syria, Iraq, Jordan, Pakistan and India.
A plant with great resistance to desiccation, its branches have the property of contracting with dryness, remaining closed and dry for many years, reopening with moisture or contact with water, regaining all its freshness and beauty. After the rainy season, the plant dries up, dropping leaves and curling branches into a tight ball, and aestivates. Within the ball, the fruits remain attached and closed, protecting the seeds and preventing them from being dispersed prematurely. The seeds are very hardy and can remain dormant for years. Moistened again in a later rainy season, the ball uncurls and the plant wakes up from its dormant state, which causes the capsular fruits to open to disperse the seeds. If water is sufficient, the dispersed seeds germinate within hours. After it curls, it is easy for the wind itself to lift and drag it large distances, making them obligatory travellers through steppes and deserts crossing the borders of various countries in Asia and disseminating their seeds for all of them.
A fraction of the seeds are dispersed in the vicinity of the parent plant by raindrops hitting a spoon-like appendix on the seeds. The seeds have a sticky coat that helps them adhere to the soil, but they also may be carried downstream by surface wash. However, seeds swept downstream do not survive.
The process of curling and uncurling is completely reversible and can be repeated many times. The ability of the plant to do this is attributed to the presence of trehalose, a disaccharide sugar involved in several mechanisms of cryptobiosis. Although the rehydrated plant sometimes is described as putting out new leaves, flowers, and fruits, this is disputed; instead, the seeds may sometimes germinate and sprout new plants while still seated in the fruit on the dead parent plant.
Anastatica has been described as the most famous tumble weed. Once dry, the ball is said to become detached and is dispersed by wind. This tumbleweed habit has been interpreted as a mechanism of avoiding burial in dunes. However, Anastatica may possess this habit only in the literature, or tumble only rarely, if uprooted by accident.
Since ancient times it was used as an element to guess the climate, since being a vegetable hygrometer, the wise man or shaman, predicted it with success. In dry weather the plant remains completely closed; in wet weather, it opens slowly; if it threatens rain, it opens in a very showy way and with more or less speed according to the proximity of discharge of the clouds.