Leaves, twigs and wood of Cotinus coggygria (Anacardiaceae) are employed in European and Chinese traditional medicine to treat
skin and mucosal injuries, fever, diarrhea, emesis and to enhance appetite. While
being a popular medicinal plant, ancient tinctorial species and common ornamental
shrub, its anatomical characteristics and tissue localization of major groups of active
compounds have not been studied yet, to the best of our knowledge. Freehand cross
sections of the stem at different developmental stages, leaf lamina and petiole were
performed. Tissue types were studied using conventional dyes (toluidine blue; congo
red and malachite green). Folin-Ciocalteu reagent, shift reagents (ammonia) and Naturstoffreagenz
A were used to complement light microscopy and autofluorescence observations of flavonoid
localization. Microscopes of type Optika XDS-3FL inverted fluorescence, and Olympus
BH-2 for observation in visible light were employed. C. coggygria stem has a typical secondary structure. The bark contains resin ducts placed in the
phloem; in younger twigs they are limited by outer sclerenchyma arches. Vascular cambium
generates distinct annual rings, with a porous structure. The vessel frequency is
of 100 – 200 mm2, and their perforations are simple. Medullar rays are narrow (1 – 2 cells). Chalcone
and aurone derivatives are present in inner wood rings aged at least 2 years, in earlywood
parts. Leaves display epidermis with anomocytic stomata on the lower surface. A hypodermis
is present on the adaxial side. The midrib contains four main vascular bundles and
cambium. The phloem encloses resin secretory cavities. The center of the midrib is
occupied by parenchyma. Palisade parenchyma is two cells deep, and spongy mesophyll
is situated towards the abaxial side. Reducing flavonoids are present in leaf mesophyll.
Acknowledgement: This work was supported by grant UEFISCDI, PN II, CT-397/30.06.2014, contract nr.
789/30.06.2014.
