The outer portion of a woody stem or root is called 'bark'. One of the main functions of bark is to protect the inner, more delicate structures. It not only keeps them from drying out, but it also guards against outside injuries of various sorts. The process by which bark is formed may go on year after year. Some of the outer portions become dry and die. The dead, broken portions give the bark a rough apperance. Some of the dry pieces are shed or broken off as the twig grows larger and older. Sometimes it is hard to tell how much of the stem should be called bark. In the palm tree, for example, there is no clear separation between bark and wood.
FACT FILE
The coconut is a large, hollow nut which grows on a palm tree. It contains a milky fluid which you can drink. The white lining is also edible and used in cooking. The coconut fibres on the outside of the shell are also used for making coconut matting and sacking.
resources: Tell me why (Chancellor Press)
image 1: http://www.post-gazette.com/image/2015/12/15/1140x_q90_a10-7_cTC_ca21,235,1236,1574/20151215HORedOakBark.jpg
image 2: https://genuinecoconut.com/wp-content/uploads/2018/01/origin-thailand-coconuts.jpg