Cross section through a stem of Viscum album

Viscum album, white mistletoe, is a hemi – parasite of Viscaceae family, growing on the branches of different trees to which it is attached by a hausterium. It is in leaf all the year.

Light micrographs below illustrate a paraffin section 10 µm thick in a portion of stem fixed with FAA. The section has been stained with PAS that specifically stains polysaccharides that appear pink, fuchsia.
General aspect of the cross section with vascular bundles arranged in a ring having poorly developed phloem but xylem is extensively developed. Under the uniseriate epidermis there is the cortical parenchyma. The central pith is partly altered.

Part of the section at higher magnification. From outside towards inside we have successively: the cuticle (yellow arrow) of the uniseriate epidermis (ep), cortical parenchyma (par co) and a vascular bundle with fibers, superposed phloem and xylem. Fibers with thick lignified walls are present on the two sides of the vascular bundle are more numerous above phloem. Scale: 100 microns