Occurrence of calcium oxalate crystals in some wild plants used in traditional medicine in Saudi Arabia

Plants are widely used in traditional medicine, but could be detrimental to patients, due to the presence of some harmful substances such as calcium oxalate (CaOx) C2CaO4 crystals. The presence, morphology and distribution of CaOx crystals were investigated in 60 wild, herbal plant species from the Al Qussim Region, Saudi Arabia. This was done via light microscopy of transverse sections of stems and leaves using light microscopy. Different types of CaOx crystals were found in only 24 of the plant species studied, the rest had no CaOx crystals. The stems of 12 plant species under study contained different types of CaOx crystals, with crystal sand being the most common. In the leaves of four plant species, druses and solitary crystals were the most frequently found types. In addition, eight species had different types of crystals in their respective stems and leaves. Rumex vesicarius had the most crystals in both its stems and leaves from all investigated species, followed by Asphodelus tenuifolius. Key words: Ca-oxalate crystals, light microscope, plant leaves, stems, Al Qussim Region.