Lesson 1 of 13 · 7 min

Root systems and the root tip

NCERT §5.1, §5.1.1, Figures 5.1–5.3

Nithya pulls up a mustard seedling and a clump of wheat from the edge of her kitchen garden. The mustard comes out with one thick root that tapers downwards; the wheat comes out with a tangled beard of thin roots, none of them thicker than the rest.

The story this chapter follows: Nithya's kitchen garden and market

Nithya's family grows brinjal, tomato, chilli, lady's finger, mustard and a china rose hedge behind the house, with a neem tree by the gate. For one week she sorts every plant part she meets in the garden, the vegetable market and the kitchen, using the terms of this chapter.

The lesson in notes

In short

A flowering plant has two parts: the root system below the ground and the shoot system (stem, leaves, flowers, fruits) above it.

Tap root system: in most dicots the radicle grows straight on into a primary root, which carries lateral roots of several orders called secondary, tertiary and so on. Example: mustard.

Fibrous root system: in monocots the primary root lives only a short time; a large number of roots from the base of the stem take its place. Example: wheat.

Adventitious roots grow from any part of the plant other than the radicle, as in grass, Monstera and the banyan tree.

Roots absorb water and minerals, anchor the plant, store reserve food and synthesise plant growth regulators.

Root cap: a thimble-shaped cover over the apex that shields the delicate tip as it pushes through the soil.

Meristematic region: a few millimetres behind the cap. Its cells are very small and thin-walled, have dense protoplasm and keep dividing.

Region of elongation: just behind the meristem. Its cells lengthen and enlarge rapidly, and this is what makes the root grow longer.

Region of maturation: further back again, where cells differentiate. Some epidermal cells here grow into fine, thread-like root hairs, which take up water and minerals.