The root

Morphology is the study of the outer form of a plant: its root, stem, leaves, flowers and fruits. A flowering plant has a root system below the ground and a shoot system above it.

In most dicots, the baby root of the seed (the radicle) keeps growing into one main primary root, which gives off side roots (secondary, then tertiary). This is a tap root system, as in mustard. In monocots, the primary root soon dies and is replaced by many roots from the base of the stem, all about the same size: a fibrous root system, as in wheat. Roots that grow from any part other than the radicle are adventitious roots: in grass, in Monstera, and the long roots hanging from the branches of a banyan tree.

Roots absorb water and minerals, anchor the plant firmly, store food (as in carrot and radish), and make plant growth regulators.

A root tip has four regions, from the tip upwards:

• Root cap: a thimble-like cover that protects the soft tip as it pushes through soil.
• Region of meristematic activity: small cells that keep dividing.
• Region of elongation: the new cells lengthen, so the root grows longer.
• Region of maturation: cells become specialised; some grow fine root hairs, which absorb water and minerals.

How to tell a stem from a root: a stem grows from the plumule (the baby shoot) and has nodes, internodes and buds. A root grows from the radicle and has none of these.