|There are three different plant species from three different families called Rose of Jericho.
- The true Rose of Jericho is Anastatica hierochuntica which belongs to the crucifer family. Its propagation stretches from Morocco to southern Iran. Anastatica hierochuntica L. is annual and does not possess the same capability as the resurrection plants. The movement of its dry and deadened branches is a purely physical mechanism, which aids propagation. When it rains, the dry and closed-up branches extend outwards and release the fruits; in dry periods they close up again. By alternation between humidification and desiccation, the process can be repeated ad infinitum, which led to the erroneous assumption that the plant was therefore still living. The plant got its name because pilgrims often used to bring it back from the Holy Land (Jericho) as a symbol and a curiosity, believing it to be a resurrection plant.
- The second «Rose of Jericho» is Asteriscus hierochuntica (syn. Pallenis hierochuntica), which belongs to the composite family. This plant is also annual and does not possess the same capability as the resurrection plants. It is found in the desert of North Africa and the Arabian peninsula, stretching as far as the Indian Sind desert. The ripe flower heads move by a hygroscopic effect. Water retention and depletion processes cause the flower heads to close in dry periods and open again within several minutes in damp conditions. These movements also take place in dead plants, as it is merely the structures of dead tissue that are responsible. The ecological purpose of these movements is that, this way, the fruits are only released from the heads when germination conditions are relatively favourable, i.e., when humidity is high.
- The third «Rose of Jericho» is Selaginella lepidophylla, which belongs to the family of moss fern plants. It is a moss fern which flourishes in the dry regions of California, Texas and Mexico and which possesses the capability of the resurrection plants. What is remarkable is the plant’s highly hygroscopic behaviour, which is attributable to the fact that the cells of the upper side of the stem have thicker walls and can absorb more water than those of the underside. Therefore, when the plant dries out, the stems close up inwards, so that the plant takes on an almost spherical shape.
The plant can stay alive as a dry, rolled-up ball for months on end, until it is awakened to new life by a heavy downpour. In the wild, the plants only grow very slowly because of the very scarce rainfall. In shops, dead plants of this kind are often sold as «Rose of Jericho». Unfortunately, their population in their natural environment has been severely decimated due to over-picking.
Selaginella lepidophylla in activ growth