Objective The aim of this research was to study anatomical features and the adaptations of fiber cells of the cassava stem for pulp-making of paper and fiberboard.

Method Anatomical structure and fiber morphology of the cassava stems were studied using optical microscopy and scanning electron microscope.

Result and conclusion The pith dimension of a cassava stem near the root was smaller than its upper part. Perennial cassava stems with branches were well lignified, and the volume ratio of pith was far below that of annual ones. Cassava stems were composed of diffuse porous wood. Their cells consisted of duct, wood fiber cells and xylem ray, and most of them were radial multiple pores. There were alternate pitting and scalariform pitting in the duct. The wood had uniseriate wood ray, a few fiber cells with bordered pit, and abundant starch granule in wood ray and fiber cells. The perennial stem fiber cell wall was 1.5 times thicker than that of the branches, and was over 2 times thicker than that of annual ones. Fiber cell length was 638-661 μm, and length-width ratio was 36.22-37.43. The ratio of wall-thickness to lumen-diameter of fiber cells was 0.14-0.32, mostly in 500-900 and 10-25 μm, thus belonging to the thin cell wall and short fiber type and meeting the requirements of paper and fiberboard industry for raw material.