For the leaves and stems, the following parameters were considered: cuticle thickness in the adaxial surface; height of epidermal cells and thickness of the outer periclinal external walls of both leaf sides; mesophyll thickness; number and distribution of secretory ducts
in the ground parenchyma of the midrib; midrib height and width; internode diameter; number of cell layers and thickness of the cortex; number of ducts in the cortex; total stem area; and total area of the vascular cylinder.
The presence of anomocytic stomata, polygonal epidermal cells with wavy anticlinal walls, helical thickened vessels, and xylem tracheary elements with crystals as well as the absence of trichomes and secretory ducts
Cortex is parenchymatous with secretory ducts
(Figure 5B) and there is no evidence of endodermis with Casparian strips nor starchy sheath.
Ducts: + = secretory ducts
lined with epithelium present; - = secretory ducts
lined with epithelium absent.
Although Frank (1868) found schizogenous development in most species, he did report apparent resorption of cells in secretory ducts
of Angiopteris and Tilia.