Depending on the age of individual peppercorns most perisperm cells will have few to many starch grains. Each oil idioblast contains one or more large droplets of pepper oil. In the immature green peppercorns oil idioblast may have numerous oil droplets of variable size, apparently during maturation the small droplets fuse to form the large, usually, single oil droplet. The pepper oil is light to dark brown when viewed by light microscopy. These birefringent euhedral crystals often pack individual cells and can be found in green, black and white peppercorns.
White peppercorns are essentially the same as the inner part of the black peppercorns.
The perisperm tissue, which makes up most of the white peppercorn, contains cells packed with intermixed oil idioblasts. . Each fruit contains a single large seed which has a very thick seed coat formed by many elongate sclereids tightly fused together. Figures 1-6 Piper nigrum fruit. Single pepper grain from ground black pepper. Cross sectional view of green peppercorn preserved in brine, cryo-sectioned.