The term " bark" is used most often in a nontechnical context and refers to all tissues external to the vascular cambium (Srivastava 1964, Esau 1965). Accordingly, the bark is an aggregation of organs and tissues that includes phloem and secondarily thickened tissues from the secondary plant body, as well as epidermis, cortex and phloem derived from the primary plant body (Esau 1965). The term bark was used by earlier authors in a technical context in reference to all dead tissues exterior to a deep-seated periderm (de Bary 1884, Büsgen and Münch 1929). Contemporary authors refer to this aggregate of dead tissues, which consists of alternating layers of periderms and associated tissues, as "rhytidome", a term often considered synonymous with the term "outer bark" (Eames and MacDaniels 1947, Esau 1965). The living organs of the bark consist of the phloem and the living tissues of the innermost periderm, the phellogen and phelloderm. All living tissues have been collectively termed the "inner bark" (Eames and MacDaniels 1947). Borger (1973) provided an excellent discussion of the development and shedding of characteristic bark types. Trockenbrodt (1990) has provided an informative survey and discussion of terminology used in the bark anatomy literature.
Borger GA 1973 Development and shedding of bark. In: Kozlowski TT (ed) Shedding of plant parts. Academic Press, New York, 205-236
Büsgen M, Münch E 1929 The structure and life of forest trees. John Wiley, New York
de Bary A 1884 Comparative anatomy of the vegetative organs of the phanerogams and ferns. Oxford Univ Press (Clarendon), London, New York
Eames AJ, MacDaniels LH 1947 Introduction to plant anatomy. 2nd ed, McGraw-Hill, New York, 427 pp
Esau K 1965 Plant anatomy. 2nd ed, John Wiley, New York, 767 pp
Srivastava LM 1964 Anatomy, chemistry, and physiology of bark. Int Rev For Res 1:204-277
Trockenbrodt M 1990 Survey and discussion of the terminology used in bark anatomy. IAWA Bull 11:141-166