Citrus Anatomy

Each segment of a citrus fruit is a compartment of the ovary, and is stuffed with small, elongated bags called vesicles, each of which contains many individual microscopic juice cells that fill with water and dissolved substances as the fruit develops. Surrounding the segments is a thick, white, spongy layer called the albedo, usually rich in both bitter substances and in pectin. And riding atop the albedo is the skin, a thin, pigmented layer with tiny spherical glands that create and store volatile oils. Flexing a piece of citrus peel will burst the oil glands and send a visible, aromatic—and flammable!—spray into the air.