As per references.

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Note added at 52 mins (2018-09-26 15:58:47 GMT)
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piliferous layer.

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Note added at 1 hr (2018-09-26 16:20:37 GMT)
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Errata. Okay Mary, I think I have it now: "cofia" is the root cap. The others: zone of active cell division, zone of cell elongation, and zone of maturation

https://www.cliffsnotes.com/study-guides/biology/plant-biolo...
As cells are added to the tip by repeated cell divisions, a young root elongates and leaves behind cells that differentiate and become the primary roots of the plant. Four areas of the young root traditionally are recognized, but except for the terminal area, are not distinctly separate. Their descriptive names are only partially correct in describing the activities taking place in each area. These regions, starting at the tip and moving upwards towards the stem, are the ****root cap, zone of active cell division, zone of cell elongation, and zone of maturation.***

The first two are compacted in the first centimeter or less of the axis with the latter two no more than 4–5 centimeters from the tip. Only the root cap and the cell division regions actually move through the soil. After cells start to elongate and mature, no further extension takes place, and the root is stationary for the rest of its life.

Root cap
The root cap is a cup-shaped, loosely cemented mass of parenchyma cells that covers the tip of the root. As cells are lost among the soil particles, new ones are added from the meristem behind the cap. The cap is a unique feature of roots; the tip of the stem has no such structure. From its shape, structure, and location, its primary function seems clear: It protects the cells under it from abrasion and assists the root in penetrating the soil. Phenomenal numbers of cap cells are produced to replace those worn off and lost as root tips push through the soil.

The movement is assisted by a slimy substance, mucigel, which is produced by cells of the root cap and epidermis. The mucigel

Lubricates the roots.

Contains materials that are inhibitory to roots of other species.

Influences ion uptake.

Attracts beneficial soil microorganisms.

Glues soil particles to the roots thereby improving the soil-plant contact and facilitating water movement from the soil into the plant.

Protects the root cells from drying out.

Root cap cells sense light in some as yet unexplained way and direct root growth away from light. The root cap also senses gravity to which roots respond by growing downward, bringing them into contact with the soil, the reservoir of nutrients and water used by plants. The root cap also responds to pressures exerted by the soil particles.

Zone of cell division
An apical meristem lies under and behind the root cap and, like the stem apical meristem, it produces the cells that give rise to the primary body of the plant. Unlike the stem meristem, it is not at the very tip of the root; it lies behind the root cap. Between the area of active division and the cap is an area where cells divide more slowly, the quiescent center. Most cell divisions occur along the edges of this center and give rise to columns of cells arranged parallel to the root axis. The parenchyma cells of the meristem are small, cuboidal, with dense protoplasts devoid of vacuoles and with relatively large nuclei.

The apical meristem of the root organizes to form the three primary meristems:protoderm, which gives rise to the epidermis; procambium, which produces xylem and phloem; and the ground meri-stem, which produces the cortex. Pith, present in most stems and produced from the ground meristem, is absent in most dicot (eudicot) roots, but is found in many monocot roots.

Zone of cell elongation
The cells in this zone stretch and lengthen as small vacuoles within the cytoplasm coalesce and fill with water. One or two large vacuoles occupy almost all of the cell volume in fully elongated cells. Cellular expansion in this zone is responsible for pushing the root cap and apical tip forward through the soil.

Zone of maturation
The elongating cells complete their differentiation into the tissues of the primary body in this zone. It is easily recognized because of the numerous root hairs that extend into the soil as outgrowths of single epidermal cells. They greatly increase the absorptive surface of roots during the growth period when large amounts of water and nutrients are needed. An individual root hair lives for only a day or two, but new ones form constantly nearer the tip as old ones die in the upper part of the zone.

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Note added at 3 hrs (2018-09-26 18:39:26 GMT)
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https://books.google.com.jm/books?id=0jGB8UHyRG0C&pg=PA165&l...
Root
External Structure
A dicotyledonous plant has a tap root system. The diagram below (shown on opening link) shows the external features of the root tip of a dicotyledonous plant. The root can be categorised into three sections — the region of cell division, elongation and maturation. The region of cell division consists of young cells that are actively dividing to form new cells. At the region of elongation (E), the cells elongate. thereby increasing the length of the root. When the root lengthens, it will push against the soil particle. To protect the root tip from injury during this process, the root tip is covered by the root cap. Behind the zone of elongation is the zone of maturation (M). There is maximum absorption of water and mineral salts in the zone.