 The pavilion of the Times Eureka Garden at this year's Chelsea Flower Show is "the nerve centre of the garden", according to the designer, Marcus Barnett. He has created it in association with the Royal Botanic Gardens, Kew. The structure has been designed by NEX architects, working on the germ of an idea from Barnett, to resemble leaves under a microscope. and leaves are what this garden is all about: our complete dependence on the plant world for our survival.  It's a thoroughly modern, cuboid structure. Complex, angular arches of precisely engineered and laminated wood interlock to form a rigid matrix of ribs or veins. The spaces are filled with "cells" of translucent plastic. as it is based on the geometry of nature, it is also very strong.  Garden design and construction has been a new field for alan Dempsey and his team at NEX, and, Dempsey says, they have learnt an enormous amount about plants, "not least about plant biology and the mathematics of plant growth and formation". The pavilion has been born of technological exploration. according to Dempsey, he used "intensive computation and 3-D digital modelling", which was then supported by the physical testing of models and full-scale mock-ups. "We went back and forward between the material and the virtual to get it right. This can be done so rapidly today, with developments in digital manufacturing, and it has transformed how we work," he says. Part of that exploration process involved the plastic cells in the pavilion's walls. The entire garden, bar the odd bit of electric lighting, is recyclable or biodegradable, and bioplastics were first considered for the pavilion's cells - but proved unsuitable. "Most architecture needs to last," Dempsey says, "whereas the goal of bioplastics is to degrade as quickly as possible, so they are not suitable for outdoor use. In the end we chose a recycled pl 