Abstract
The rare plant Rheum palaestinum (Polygonaceae) is a perennial hemicryptophyte that grows during the rainy winter in desert mountainous areas in Israel and Jordan that receive an average annual rainfall of ca. 75 mm. It produces between one and four large round leaves that are tightly attached to the ground and form large rosettes of up to 1 m2. These leaves differ markedly from the typical small leaves of most desert plants. Moreover, they have a unique 3D morphology resembling a scaled-down mountainous area with well-developed steep drainage systems, raising the question which selective agents were involved in their evolution. We propose that the large leaves collect rainwater that then infiltrates the soil surrounding the root. We measured the seasonal course of leaf growth, examined the area of wet soil surrounding the root after actual and simulated rain, and modeled the water harvesting capacity using the plant leaf area and the weekly precipitation. We show that even in the slightest rains, water flows above the veins to the leaf’s base where it irrigates the vertical root. A typical plant harvests more than 4,100 cm3 of water per year, and enjoys a water regime of about 427 mm/year, equivalent to the water supply in a Mediterranean climate. This is the first example of self-irrigation by large leaves in a desert plant, creating a leaf-made mini oasis.
References
Barthlott W, Neinhuis C (1997) Purity of the sacred lotus, or escape from contamination in biological surfaces. Planta 202:1–8
Danin A (1969) On our and other’s rhubarb. Teva Veaaretz 11:89–90 (in Hebrew)
Danin A (1972) Mediterranean elements in rocks of the Negev and Sinai deserts. Notes R Bot Gard Edinburgh 31:437–440
Danin A (1983) Desert Vegetation of Israel and Sinai. Cana, Jerusalem
Danin A (1999) Desert rocks as plant refugia in the Near East. Bot Rev 65:93–170
Evenari M, Shanan L, Tadmor N (1982) The Negev. The challenge of a desert, 2nd edn. Harvard University Press, Cambridge
Fahn A (1964) Some anatomical adaptations of desert plants. Phytomorphology 14:93–102
Fahn A, Cutler DF (1992) Xerophytes. Gebrüder Borntraeger, Berlin
Feinbrun N (1944) A new Rheum species from Palestine. Palest J Bot Jerusalem Ser 3:117–118 plate III
Hillel D, Tadmor N (1962) Water regime and vegetation in the central Negev highlands of Israel. Ecology 43:33–41
Smith WK (1978) Temperature of desert plants: another perspective on the adaptability of leaf size. Science 201:614–616
Zohary M (1966) Flora Palaestina, Vol. I. The Israel Academy of Sciences and Humanities, Jerusalem
Zohary M (1973) Geobotanical foundations of the Middle East. Gustav Fischer, Stuttgart
Author information
Authors and Affiliations
Corresponding author
Additional information
All authors contributed equally to this paper.
Rights and permissions
About this article
Cite this article
Lev-Yadun, S., Katzir, G. & Ne`eman, G. Rheum palaestinum (desert rhubarb), a self-irrigating desert plant. Naturwissenschaften 96, 393–397 (2009). https://doi.org/10.1007/s00114-008-0472-y
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00114-008-0472-y