An electron microprobe (EMP) analysis of silica (SiO,) deposition in the epidermis of developing internodes of the perennial scouring rush (Equisetum hyemale var. affine) indicates that SiO, is first detected in the stomata1 apparatus beginning with internode 3, then the epidermal papillae (internode 8), and finally in radial cell walls of the long epidermal cells (internode 10). This process i...
