The Rose of Jericho is, without a doubt, a striking and peculiar plant. Commonly sold in herbal shops and medieval markets, all kinds of mystical, magical and sacred properties are attributed to this plant. Some of the superstitions that surround this curious plant are to absorb negative energies, attract good fortune, bless homes and even protect its inhabitants from evil spirits. And most of these properties are attributed to him due to an extraordinary capacity: that of resurrecting. Back to life. But, let us start at the beginning.
What is the “rose of Jericho”?
From the outset there is a fairly common confusion between two very different plants , both with the same name, which have nothing to do with each other; Except that both lack therapeutic properties and, despite what their common name indicates, they are not roses —they do not even belong to the Rosaceae family—, nor do they grow in the city of Jericho.
On the one hand, there is Selaginella lepidophylla , a kind of lycophyte, related to ferns. This is the most common species found in medieval markets, which is ironic, since it is native to the Chihuahua desert , Mexico, and in the Middle Ages it did not exist in Europe. Morphologically, it has branches that fork towards the end, flattened, and covered with tiny scale-shaped leaves.
On the other hand, and much closer to Jericho, is Anastatica hierochuntica , a plant of the cruciferous family —from the same family as radish, arugula, cabbage or mustard— native to the deserts of Arabia and Sahara, and around the Red Sea. It is a plant with the largest leaves, oval in shape, and much rarer to find in markets or stores.
As mentioned, popular belief attributes to the roses of Jericho —both the lycophyte and the cruciferous— the ability to resurrect, to come back to life, but it is not a real resurrection. To resuscitate it is necessary, first, that the organism is dead. And when these plants die they do not live again .
La cryptobiosis
There are two characteristics that both species share. One is habitat: both are desert species. And the second is the ability of anhydrobiosis , that is, the ability to survive desiccation. And it is that, in reality, what people perceive as death is that state of anhydrobiosis.
Anhydrobiosis is a type of cryptobiosis , which is the name given to certain states that some living beings may have, during which all metabolic activity stops and remains dormant, until conditions are favourable. Apart from anhydrobiosis, which happens to survive drought, other types of cryptobiosis are osmobiosis , to protect itself from osmotic stress caused by excess salinity in the environment, or cryobiosis , or freezing survival.
Survival against desiccation
When there is no water in the environment, the plant dehydrates, losing up to 95% of its water. In doing so, the mineral salts of the plant are highly concentrated – they do not evaporate – and can damage the tissues. To prevent this, the plant synthesizes huge amounts of trehalose , a disaccharide formed by the union of two glucose molecules. This sugar forms with the remaining water a kind of dense syrup that protects the tissues from mineral salts.
Let us remember that this process happens in plants that are extraordinarily separated, in evolutionary terms , which seems to indicate that different groups of plants acquired the same type of adaptation as a solution to the same problem; an example of evolutionary convergence . Although in the case of S. lepidophylla , it has also been shown that it uses polyols, such as sorbitol or xylitol, to form this kind of protective syrup.
In the process of anhydrobiosis, chlorophyll and other pigments degrade; Added to desiccation, it makes the plant take on a brown, dry and brittle appearance; it folds back on itself and gives the appearance of a fragile ball, which rolls through the desert moved by the wind.
But everything returns to normal when the plant is exposed to water. Upon contact with moisture, the plant rehydrates. The stored trehalose then serves as the first nutritional resource , while the leaves unfold again and chlorophyll reforms, in time to resume the function of photosynthesis, provided there is sufficient water.
References:
Adams, R. P. et al. 1990. Comparison of free sugars in growing and desiccated plants of Selaginella lepidophylla. Biochemical Systematics and Ecology, 18(2), 107-110. DOI: 10.1016/0305-1978(90)90044-G
Crowe, J. H. et al. 1992. Anhydrobiosis. Annual Review of Physiology, 54, 579-599. DOI: 10.1146/annurev.ph.54.030192.003051
HEGAZY, A. K. et al. 2006. Anatomical Significance of the Hygrochastic Movement in Anastatica hierochuntica. Annals of Botany, 97(1), 47-55. DOI: 10.1093/aob/mcj011
Pampurova, S. et al. 2014. The desiccation tolerant secrets of Selaginella lepidophylla: What we have learned so far? Plant Physiology and Biochemistry, 80, 285-290. DOI: 10.1016/j.plaphy.2014.04.015
Wickens, G. E. 1998. Ecophysiology of Economic Plants in Arid and Semi-Arid Lands. Springer Science & Business Media.
