This is a genuine image of a cross section of grass leaf under a microscope. No part of the leaf is "smiling" in any literal sense, of course, but the round features known as "vascular bundles" do ...

The cross-section of a leaf reveals its complex structure. The waxy cuticle surface on the outside protects the leaf and prevents excess water loss. The palisade cells at the upper side are packed ...

The researchers embedded pieces of leaf in plastic and cut cross-sections thinner than a single cell to observe each leaf's microscopic layout. This allowed them to test the underlying ...

The pits look as if water could sluice through easily in a tickled-leaf emergency. Cell arrangement itself looks specialized for expanding and shrinking. A pulvinus cross section reveals a pattern ...