Lesson 1 of 10 · 6 min

Three tissue systems

NCERT §6 introduction, §6.1

In the school lab, Meera slices a sunflower stem as thin as she can with a new blade, floats the slices in water and stains the thinnest one pink. Under the microscope the circle breaks up into rings, patches and a pale centre.

The story this chapter follows: Meera's slides in the school lab

Meera spends a week of lab periods cutting thin sections of sunflower and maize roots and stems, and of mango and grass leaves, with a blade. Her teacher, Mr Joseph, makes her name every layer she sees under the microscope using the terms of this chapter.

The lesson in notes

In short

Anatomy is the study of the internal structure of an organism. In a plant, cells make up tissues and tissues make up organs, and each organ has its own internal plan.

Monocots and dicots differ inside as well as outside, and internal structure also changes as plants adapt to different environments.

Grouping tissues by where they sit and what they look like gives three tissue systems: the epidermal system, the ground (fundamental) system and the vascular (conducting) system.

Epidermal system: the outer covering, made of epidermal cells, stomata and appendages such as hairs and trichomes.

Ground system: everything except the epidermis and the vascular bundles. It forms most of the plant body and is divided into cortex, pericycle and pith.

Vascular system: xylem and phloem, which together form vascular bundles and carry water, minerals and food.

To compare roots, stems and leaves, their mature zones are cut across (transverse sections) and viewed under the microscope.