Increasing vascular bundle density has long been believed to be a key initial step in C 4 plant evolution. However, the regulatory mechanisms governing leaf vein density have remained elusive.

In other words, the "smiley faces" are just an illusion created by viewing a slice of the leaf's round vascular bundles from above, through a microscope lens. By Bethania Palma.

Once inside the leaf (Fig. 1), microplastics move through spaces between plant cells and can also accumulate inside tiny hair-like structures, called trichomes, on the surface of leaves.

IN the course of a broad investigation of the comparative anatomy of the monocotyledons at present in progress at the Jodrell Laboratory, Kew, an exceptionally interesting arrangement of vascular ...