Often you will notice a powdery white coating on raspberry and blackberry stems, as well as on a variety of fruits, including plums, blueberries, grapes and apples, and on the leaves of plants as well. This outer layer is referred to as bloom, and is produced by the plant’s epidermal cells. It consists particles of cutin, a waxy, water-repellent substance, embedded in epicuticular wax. One of its main functions is to reduce the loss of water. In repelling water, bloom also prevents bacteria and mold spores as well as air pollutants from entering the plant. In addition, it is responsible for the self-cleaning mechanism of plants. Bloom prevents dirt and other particles from sticking to the plant, so that when water rolls off the plant, it takes the dirt away. Using biomimicry, scientists have developed paint and textiles that stay clean by repelling dirt and water. Bloom is routinely harvested to polish and protect cars and furniture.
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