Bark (botany) rope, used for example in the rigging of Viking age longships. Among the commercial products made from bark are cork, cinnamon, quinine (from the bark of Cinchona) and aspirin (from the bark of willow trees). The bark of some trees notably oak ("Quercus robur") is a source of tannic acid, which is used in tanning. Bark chips generated as a by-product of lumber production are often used in bark mulch in western North America. Bark is important to the horticultural industry since in shredded form it is used for plants that do not thrive in ordinary soil, such as epiphytes.
Bark bread known from the 1890s, and in Finland "pettuleipä" (literally "pinewood-bark bread") was produced as ersatz bread during the Finnish Civil War of 1918. Finger sized twigs and branches were collected from deciduous trees and shrubs, and the bark split and the inner bark (the phloem and sometimes the vascular cambium) collected while still fresh. The yellow or green inner bark (depending on tree species) was dried over open fire, in an oven or dried in the sun for a few days. A mortar or mill was used to grind the bark to a fine powder to add to the flour.