THE BIOLOGY OF RUDRAKSHA

Rudraksha, used throughout India and Southeast Asia in religious jewel lery, is the stony endocarp of a tree distributed from northern Austra lia to southern Nepal. This article summarizes its biology, particular ly recent research on the remarkable fruit colour. The iridescent blue colour is caused by a remarkable structure, an 'iridosome', It is sec reted by the epidermal cell, and is located above the plasmalemma and beneath the adaxial wall. Cellulosic layers within the iridosome const ructively interfere with blue wavelengths, causing an intense colour p roduction at 439 nm, This colour persists in senescing fruits and may enhance their dispersal, The transparency of the cuticle at longer wav elengths allows photosynthesis to occur in the fleshy green exocarp ti ssue, enhancing the carbon balance of the tree. More research will cer tainly reveal the evolution of this remarkable phenomenon, as well as the origins of the rudraksha's cultural use.