Question
Biology Question on Anatomy of Flowering Plants
Which of the following is not a part of epidermal tissue system?
Companion cells
Trichomes
Root hairs
Guard cells
Companion cells
Solution
The epidermal tissue system consists of the epidermis derived from protoderm and its associated structures; the epidermal outgrowths. The stomata are minute pores which occurs on epidermal surface of leaves and also some herbaceous stems. Each stoma or pore is bounded by two specialized kidney shaped epidermal cells,
called guard cells. The guard cells are also surrounded by other specialized epidermal cells called subsidiary cells or accessory cells. From epidermal cells, various unicellular or multicellular epidermal outgrowths have originated and they are present all over the plant parts. These are called trichomes. In roots, tubular, unicellular, unbranched outgrowths are called root hairs which increase the surface for absorbtion. Companion cells are part of phloem which in turn are a part of vascular tissue system and not epidermal tissue system.