histogen theory
Quick Summary
The histogen theory in botany proposes that the growing tip of a plant, such as a stem or root, is composed of three distinct layers of cells called histogens. Each histogen is responsible for developing into a specific tissue system within the plant.12
The three primary histogens are:
* Dermatogen: This outermost layer develops into the epidermis, which protects the plant.12
* Periblem: Located beneath the dermatogen, this layer forms the ground tissues, including the cortex and pith.12
* Plerome: The innermost layer, the plerome, differentiates into the vascular tissues, such as xylem and phloem, which are responsible for transport and support.12
In some root apices, a fourth histogen, the calyptrogen, is identified as the producer of the root cap. While the histogen theory provides a framework for understanding plant tissue development, its application can vary, and the concept of a "quiescent centre" in root tips has further clarified these developmental processes.3
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
