Definition

Noun (Botany): The outer tissue of bark on a tree or woody plant; a protective layer of dead, suberized (corky) cells that forms part of the periderm. It functions primarily to reduce water loss and protect against physical damage and pathogens.

Usage

"Phellem" is a technical, scientific term used specifically in botany and plant anatomy. It is not used in everyday conversation.

Examples: * The phellem provides an effective barrier against desiccation. * In the study of tree bark, the phellem, phellogen, and phelloderm together constitute the periderm. * The thickness of the phellem layer varies significantly between different tree species.

Advanced Usage

• Formation: Phellem is produced inwardly by the phellogen (cork cambium). As new phellem cells form, the older, outer layers die and become the protective cork.
• Commercial Cork: The commercially harvested cork from the cork oak () is a particularly thick and renewable layer of phellem.

Variants and Related Words

• Cork: The common, non-technical term for phellem, especially when referring to its material properties.
• Periderm: The collective term for the secondary protective tissue in plants, consisting of the phellem (cork), the phellogen (cork cambium), and the phelloderm.
• Suberin: The waxy, hydrophobic substance that impregnates the cell walls of phellem, making it impermeable to water and gases.
• Phellogen (noun): The meristematic layer of cells (cork cambium) that generates the phellem.
• Phelloderm (noun): The layer of living parenchyma cells produced inwardly by the phellogen.

Synonyms

• Cork (in a botanical or material context)
• Cork tissue

Antonyms

• Phloem: The living, inner bark tissue responsible for transporting sugars and nutrients.
• Vascular cambium: The meristematic layer that produces secondary xylem (wood) and phloem, not protective bark tissues.

Noun

1. (botany) outer tissue of bark; a protective layer of dead cells