BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VIII. FUNDAMENTALS OF PLANT MORPHOLOGY AND ANATOMY

Morphology and Anatomy of the Root

Root Zones

In this context, It is worth noting that during The formation of The ROOT System, seedling rootlets undergo noticeable changes. In young plant seedlings, the rootlet differentiates into a series of morphogenetic zones. Using a magnifying Glass or Microscope, one can observe that the root tip is covered by a root cap. As it penetrates the soil, its outer Cells become mucilaginous and slough off, while new ones emerge to replace those that die off
. They are replenished thanks to a specific meristematic tissue—the calyptrogen—located near the root cap.

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Fig. 56. Cytology/practical/54.html">Longitudinal section of the root tip: A - absorption zone; B - elongation zone;

C - division zone; a - dermatogen, b - periblem, c - plerome;

D - root cap, e — calyptrogen

Beneath the root cap lies the growing point, or Cell Division zone (Fig. 56), 2–3 mm in length. It consists of living cells containing a significant reserve of nutrients and Genetic information. Within the division zone, the following cell layers (histogens) are distinguished: 1) dermatogen, 2) periblem, 3) plerome.

The elongation zone is 3–5 mm long. Here, cells elongate and acquire a specific shape and size, which drives the longitudinal growth of the root.

Further up lies the root Hair zone, or absorption zone. Here, new root hairs are continuously formed in the growing part and always remain at a certain distance from the tip of the rootlet. At the opposite end of the zone, the root hairs die off after absorbing water and dissolved mineral salts from the soil.

A root hair is an outgrowth of the outer Cell wall of the epiblem.

Located further up is the lateral root zone, or branching zone. Lateral roots develop endogenously from the main root. The function of this zone is the anchorage and fixation of the plant in the soil, as well as the expansion of the organ's nutrient-absorbing surface.