Periderm Periderm Phellogen cork cambium Phellem cork Phelloderm

Periderm

Periderm • Phellogen – cork cambium • Phellem – cork • Phelloderm – parenchyma like tissue

Periderm, Cork, and Bark • Bark = all the tissues outside of the vascular cambium – Inner Bark includes all the tissues from the secondary phloem outward to the phelloderm (or phellogen) – Outer Bark includes the periderm and all the tissue outside of it • Rhytidome – all the successive periderms that develop – bark external to the last formed periderm

Periderm developing on a branch

Development of Periderm

Periclinal divisions of sub-epidermal cells leads to the development of phellogen

In Quercus alba, the phellogen originates in sub-epidermal cells Phellogen has produced 4 layers of phellem (cork) and one layer of phelloderm

In Solanum (nightshade), the phellogen arises from the epidermis

Phellogen in Clematis originates deep in stem tissue from phloem parenchyma cells below the fiber caps Phellogen (cork cambium) Vascular cambium

In grape vines, the phellogen also originates in the primary phloem

Periderm with tannins Oak Clusia Tannins deter insects and other animals from feeding on bark, adding to the protective capacity of bark.

Tilia periderm

Lenticels

Lenticels in moonseed form prior to periderm formation Cuticle

Lenticel in Aristolochia

Sambucus lenticel

Lenticel in ivy stem

Rhytidome

Robinia rhytidome

Pine White ash Walnut Sweetgum Paper birch Tilia Crepe myrtle White Oak

Commercial cork is obtained from Quercus suber, the cork oak tree

Harvesting and Regrowth