The leaves are triangular in cross section, the hypodermis usually with a double layer of cells; resin ducts ( 1-) 2-3 ( 4 ), medial, occasionally 1 internal, stele oval in cross section; outer walls of endodermal cells not thickened; vascular bundles 2, distinct, the xylem strands often connate.
42.
The stem is surrounded by a continuous ring of sclerenchyma that separates it from the root mantle . " T . singularis " stem transverse sections have the same basic structure as Psaronius, but are composed of central vascular bundles having smaller, O-and C-shaped forms, or wavy segments having a short, rounded or fat configuration.
