Scots pine (Pinus sylvestris) stem. Light micrograph of a section through the epidermis removed from a stem of a Scots pine tree. Groups of star-shaped crystals (black-white) of calcium oxalate, known as druses, can be seen scattered throughout the tissue, along with stomata (pores, round, white), their guard cells (sausage-shaped) and slightly plasmolysed cytoplasm with chloroplasts, nuclei and vacuoles. Magnification: x37 when printed 10 centimetres wide.