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

Anatomical Structure of the Root

The Water/140.html">Anatomical Structure of the ROOT corresponds to the Functions it performs and the conditions of its growth. In natural environments, roots must overcome significant obstacles and adapt to various living conditions; therefore, all Tissues and their histological elements are arranged to jointly carry out absorptive, conductive, and mechanical functions. When a seed germinates, the embryonic root is the first to grow and penetrate the soil. It is precisely on this root that the anatomical STRUCTURE OF THE root tip can be best studied (see Fig. 58).

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Fig. 58. Introduction/19.html">Primary Structure of the German iris root:

A - epiblema, 1 - root Hair; B - primary cortex:

2 - exodermis, 3 - mesodermis, 4 - endodermis; C - central cylinder: 5 - pericycle,

6 - pith parenchyma, 7 - primary xylem, 8 - primary phloem.

The structure of the root is not uniform along its entire length. Examining a Cytology/practical/54.html">Longitudinal section of a typical root tip reveals several distinct zones that differ in Structure and function.

The root tip is covered by a root cap. The root cap is a specialized structure that protects the apical meristem—the root growth cone—and helps the root penetrate the soil. It consists of living parenchymatous Cells coated with mucilage, which slough off as the root advances through the soil. The root cap is capable of mediating root georeception. This function is facilitated by the central columella, whose cells contain starch-bearing amyloplasts that act as statoliths. The Origin of the root cap varies among different plant species. During ontogeny, an initial layer—the calyptrogen—appears, which regenerates the root cap from within. The root cap persists throughout the entire life of the plant root. It is most highly developed in rapidly growing roots. Located beneath the root cap is the apical meristem—the root growth cone.