the outer layers of tissue of woody roots and terns consisting of the cork cambium and the tissues produced by it. such as bark.

Merriam-Webster Online Dictionary
periderm (noun)
an outer layer of tissue , especially a cortical protective layer of many roots and stems that typically consists of phellem, phellogen, and phelloderm
periderm (Wikipedia)

Bark of mature Mango (Mangifera indica) showing lichen growth

Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes the innermost area of the periderm. The outer bark in older stems includes the dead tissue on the surface of the stems, along with parts of the innermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the last formed periderm is also called the rhytidome.

Products derived from bark include: bark shingle siding and wall coverings, spices and other flavorings, tanbark for tannin, resin, latex, medicines, poisons, various hallucinogenic chemicals and cork. Bark has been used to make cloth, canoes, and ropes and used as a surface for paintings and map making. A number of plants are also grown for their attractive or interesting bark colorations and surface textures or their bark is used as landscape mulch.

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