The inner bark of red and yellow cedar (Callitropsis nootkatensis & Thuja plicata) has been used for basketry and garment production by the people of the Pacific Northwest coast for centuries. Cedar bark baskets are sometimes mistaken for spruce root, this is often the case with the Tsimshian and Makah baskets misidentified in museum catalogues; in these baskets the foundation is made from the cedar bark and the weft is made from the spruce root. Cedar bark looks ‘spongy’ and feels soft and flexible while the spruce root looks and feels like wood.
Spruce root is usually debarked for basketry and lashings and its wood looks very similar to the stem; the heartwood is discarded, the sapwood is retained. Anatomically the sapwood is xylem while the bark is a secondary phloem. The phloem has 3 types of cells: sieve elements, parenchyma cells and sclerenchymatous cells. Sclerenchymatous cells usually measure 0.1-3 mm in length and arranged in tangential rows, used as fibers. Calcium oxalate crystals are present between these cells and may assist in plant identification.
Micrographs of cedar stem wood and bark can be found in M. Florian 1990, The Conservation of Artifacts Made from Plant Materials.
Micrographs of cedar stem wood can also be found in Heady et al. 2010, Identification of the woods used to make the Riley cabinet A historically-significant example of early Australian, convict-built, furniture, IAWA Journal, Vol. 31 (4), 385–397. This paper explains the technique of small sample removal from the objects of historic significance & discusses limitations and advantages of SEM and light microscopy in wood species identification.
Panshin, A. J. & C. de Zeeuw. 1980. Textbook of Wood Technology, McCraw-Hill.