| Although only the suberized phellem tissue is obtained whereas the phellogen and phelloderm are digested during the enzymatic treatment, we use the term periderm instead of phellem following a number of prior authors. |
| Commonly only phellem cells are produced, but in a few, including several species of Pachycereeae, phellem and phelloderm cells may be produced. |
| It has been widely suggested that phellem, a corky outer layer derived from the cork cambium may function as aerenchyma, but until now no-one had tested that hypothesis. |
| As phellem cells develop, they become suberized and then die, forming a protective layer. |
