Fig. 2

SEM images of the epidermis and margin of the pith cavity in the culm (left) and rhizome (right). a, b Epidermis and outer cortex in transverse section; c, d epidermis in radial section; e, f margin of pith cavity in transverse section; g, h margin of pith cavity in radial section. Arrow in a fiber bundle, arrow in f orientated vascular bundle irregularly, arrow in g and h pith paper