Spruce leaf. Light micrograph (LM) of a section through a leaf of the spruce tree (Picea sp. ). Stomata leaf openings (at lower right) can be seen on the underside of the leaf. The leaf's outer cell layers (red) include the impermeable cuticle on the very outside and then a layer of upper epidermis cells. The other leaf cells are tightly- packed palisade cells and, towards the centre of the leaf, irregular mesophyll cells with air spaces (white). Both these cells contain the green photosynthetic pigment chlorophyll with which leaves produce nutrients from sunlight. The spruce is common in cold areas of North America, Asia and Europe. Magnification: x30 at 5x7cm size.