Cortex
/ˈkɔrˌtɛks/
Definition
Cortex refers to the layer of mostly ground tissue found between the epidermis, the outer protective layer, and the vascular tissues in roots and many young stems. It is made largely of parenchyma cells and often stores starch or water, while also helping move materials inward to the xylem and phloem. In roots, the cortex usually ends at the endodermis, which separates it from the vascular cylinder.
Function in Plants
- Storage in young organs: In many young stems and roots, cortex cells store starch and water. This reserve can support new growth before leaves or roots are fully active.
- Pathway for internal movement: The living cells in cortex help move water and dissolved substances sideways between outer tissues and the vascular system, the transport tissue that carries water and sugars through the plant.
- Support and aeration: Depending on the species, cortex may provide flexible support or contain large air spaces. Those air spaces are especially useful in wetland plants, where roots need oxygen in waterlogged soil.
- Clue in root crops and damage: In crops such as carrots and beets, much of the edible tissue includes cortex. Its condition can also matter in diagnosis, because decay, cracking, or browning there may point to stress, disease, or poor storage.
Related Terms
Epidermis
Epidermis is the outermost layer of cells covering young leaves, stems, roots, flowers, fruits, and seeds. It is a…
Cambium
Cambium is a thin layer of actively dividing cells in vascular plants, found between xylem and phloem in stems, roots…
Xylem
Xylem is the plant vascular tissue that carries water and dissolved minerals from the roots to stems and leaves. It…
Phloem
Phloem is the plant vascular tissue that transports sugars and other organic nutrients made during photosynthesis from…
Vascular tissue
Vascular tissue is the plant transport system, made of xylem and phloem. Xylem carries water and dissolved minerals…
Root
Root refers to the plant organ, usually below ground, that anchors the plant and absorbs water and dissolved minerals…
Stem
Stem refers to the main aboveground plant structure that supports leaves, buds, flowers, and fruits, and connects them…
Casparian strip
Casparian strip is a band of waterproof material, mainly lignin, in the radial and transverse walls of endodermal cells…