Lesson 3 of 10 · 6 min
Hairs and ground tissue
NCERT §6.1.1, §6.1.2
Meera rubs a tomato stem and her fingers smell sharp and green. Under a hand lens, the stem is furry with hairs, some with little round heads. Are these the same as the hairs on a root?
The lesson in notes
In short
Root hairs are single-celled outgrowths of epidermal cells. They take up water and minerals from the soil.
Hairs on the stem are called trichomes. In the shoot they are usually multicellular, branched or unbranched, soft or stiff, and some secrete substances.
Trichomes help reduce the water lost in transpiration.
Ground tissue is every tissue other than the epidermis and vascular bundles. It is built of simple tissues: parenchyma, collenchyma and sclerenchyma.
In primary stems and roots, parenchyma is found in the cortex, pericycle, pith and medullary rays.
In leaves the ground tissue is the mesophyll: thin-walled cells that contain chloroplasts.