Scanning electron micrograph of Buddleia (Buddleja davidii) leaf. This plant thrives in dry city areas due to the meshwork of hairs (white) on the underside of its long, narrow leaves that prevent water loss. Numerous stomata (pores) flanked by guard cells (bulbous green structures) are also visible. Guard cells control the opening and closing of the stomata as required to allow exchange of gases into and out of the leaf. Magnification: 450x. Width of hair is approximately 8 micrometers. Supplied by Lauren Holden, courtesy of Wellcome Images.