Desert Rhubarb - The First Plant Shown to Organise its Own Irrigation?
Scientists from the University of Haifa have shown that Desert Rhubarb, has evolved to ensure that it makes more of the limited rainfall in the Negev Desert than other competitor plants.
Desert Rhubarb (Rheum palaestinum) grows in Israel and Syria, but was studied in the Negev desert by the University of Haifa. Desert Rhubarb is a perennial hemicryptophyte, that grows during the rainy winter in mountainous desert areas where the average annual rainfall is only 75 mm (just under 3 inches).
- » See also: Oceans’ Ability to Absorb Carbon & Protect Against Climate Change Weakening
- » Get EcoWorldly by RSS or sign up by email.
The basis of Desert Rhubarb’s advantage are the one to four large round leaves that are tightly attached to the ground and cover a circular areas of up to 1 m² (around 11 ft²). This is very different to many desert plants which have small leaves to minimise moisture loss. The leaves have a “unique 3D morphology” that when photographed in close up, reminds avid hobby photographer Lev-Yadun, of the stark, rugged topography in the mountainous regions in which the Desert Rhubarb grows.
The scientists explain that these deep and wide depressions in the leaves create a “channeling” mountain-like system by which the rain water is channeled toward the ground surrounding the plant’s deep root.
The scientists showed, that even in the slightest rains, water flows through this channel system to the leaf’s base where it irrigates the vertical root. A typical plant harvests more than 4 litres (over a gallon) of water per year which is 16 times greater than normal small leafed plants use. This means its water regime is equivalent to about 427 mm a year (around 17 inches a year), which is similar to the water supply in a Mediterranean climate.
Additional research into the mechanics of the plant finds that the plant not only funnels the water to its roots, but the water is able to penetrate 10 cm into the soil, 10 times deeper than if the rain landed by itself on the desert sand. A tough waxy surface on the leaves, lends additional support in funneling the water to the roots where it is needed.
This is the first example of self-irrigation by large leaves in a desert plant, creating a leaf-made mini oasis.
Photo Sources: Desert Rhubarb - by Prof. Gidi Ne’eman at Eureka; Desert Mountains - k1llYRid0ls on Flickr under a a Creative Commons license.
