Figure 3.
Photomicrographs of the petiole of the five Ulmus species (×100). The black bars mean 100 µm. cr, crystal; col, collenchyma cells; dr, druse; h, hair; ep, epidermis; par, parenchyma cell; xy, xylem; a, vascular bundle thickness; b, midrib diameter; c, vascular bundle width; d, vascular bundle height. UD, Ulmus davidiana var. japonica; UP, U. parvifolia; UM, U. macrocarpa; UL, U. laciniata; UPU, U. pumila.