suberin
Noun
Meaning
A material found in the cell walls of cork. It is a modification of lignin.
Source: Webster's dictionaryExamples
Additional layers may be formed containing lignin in xylem cell walls, or containing suberin in cork cell walls.
The evolution of the wood fiber lignin and the bark-sealing, waxy substance suberin variously opposed decay organisms so effectively that dead materials accumulated long enough to fossilise on a large scale.