1. Epidermal tissue system and its diagnostic features

2. Epidermal tissue system
Epidermis forms the outer most boundary of primary plant body
Structures associated with the epidermis:
Stomata
Cuticle
Trichomes/hairs
Glands/secretory cells
Idioblast cells

3. Functions of epidermis
Stomata- concerned with Gaseous exchange
Cuticle and fatty material- restrict transpiration
Tough cuticle and compact cells provide definite shape to the body
Epidermis having root hairs is thin walled and absorbs water (Epiblema)
Site of photo-reception-plays imp role in circadian leaf movement and photoperiodic induction
Epidermal protoplast stores various products of metabolism

6. Special types of epidermis
Epidermis as periderm in mature trees - protective role
Usually epidermis is single layered
2 layered epidermis- Ficus elastica
Multilayered epidermis is found in Nerium leaf, Pepromia etc

7. Multiple epidermis- when protoderm layer of the leaf divided parallel with the surface and give rise to multiple epidermis e.g. Pepromia pereskiaefolia

8. Specialized cells of epidermis

9. Guard cells guard cells in Monocots Guard cells in Dicots
dumbell shape
Guard cells in Dicots
Kidney shaped

10. Cork cells /silica cells-found in Gramineae/Cyperaceae
Bulliform cells: elongated cells in epidermis of Poaceae
Idioblast cells: containing tannins, oils and crystals eg in Poaceae

11. Cuticle deposition in epidermis

12. Secretory cells

13. Trichomes

14. Modified epidermis : Ontogeny is same as epidermis
Velamen of root; multilayered epidermis which function is water storage.
Epidermis with chloroplast –found in shady plants
Epidermis possessing anthocyanin pigments in their vacuoles: Rhoeo dicolor