Dermal Tissue

dermal tissue

covers the outer layer of plants

herbaceous plants covered with

epidermis

woody plants epidermis

tears and dries out eventually forming periderm (bark) 

dermal tissue structure/characteristics (7)

• layers of cells covering surface of entire plant

• layer is thin + transparent

• trichomes are tiny hairs protecting from epidermis

• root hairs are elongated epidermal cells in the root

• epidermal tissues in leaves secrete a waxy cuticle

• specialised epidermal cells called guard cells contain chloroplasts

• some epidermal cells can secrete poisonous or bad-tasting substances 

epidermal tissue - layers of cells covering surface of entire plant - function

acts as a barrier to fungi + other microorganisms + pathogens (disease causing organisms) 

epidermal tissue - layer is thin + transparent - function

allows for light to pass through, allowing photosynthesis to occur in the tissues below 

epidermal tissue - trichomes - function

leaf trichomes trap water vapour on the surface of the leaf to prevent further water loss 

trichomes

leaf trichomes are tiny hairs that trap water on the surface of leaves to prevent water loss 

dermal tissue - root hairs - function

increase surface area for the absorption of water from the soil 

dermal tissue - waxy cuticle - function

prevents water loss from leaves 

dermal tissue - guard cells containing chloroplasts - function

controls the opening and closing of breathing pores / stomata 

dermal tissue - secrete poison / bad tasting substances - function

bitter taste deters browsing and grazing by animals (eg: giraffe) 

special features on epidermal tissue

1. root hairs
2. trichomes
3. stomata

stoma

a stoma is a pore found in the leaf and stem epidermis that allows for gaseous exchange

stomata in epidermis

allow O2, CO2, water vapour to enter and exit the leaf 

guard cells contain

chloroplasts for photosynthesis

opening and closing of guard cells determined by

turgor pressure of the 2 guard cells 

stoma day vs night

day = guard cells turgid = open stoma
night = guard cells floppy = closed stoma 

why is an epidermal cell transparent (look / appearance, not function)

no chloroplasts

dermal tissue divided into

epidermis, periderm 

cells of epidermis (5)

• one layer of cells closely packed

• cuboidal shaped cells

• no chloroplast = transparent

• cuticle (waxy layer) prevents water loss

• stomata (pores) allow transpiration and gaseous exchange 

layer of cells covering surface of entire plant: function

acts as barrier to fungi and other microorganisms and pathogens 

layer is thin and transparent: function

allows for light to pass through, thereby allowing for photosynthesis in tissues below 

trichomes which are tiny hairs projecting from surface of epidermis: function

leaf trichomes trap water in area above stomata and prevent water loss 

root hairs are elongations of epidermal cells in the root: function

root hairs maximise the surface area over which absorption of water from soil can occur 

epidermal tissues in leaves covered with waxy cuticle: function

prevents water loss from leaves 

epidermal tissues contain guard cells containing chloroplasts: function

guard cells control opening and closing of pores known as stomata 

some plant epidermal cells can secrete poisonous or bad tasting substances: function

the bitter taste of the substance deters browsing and grazing by animals 

special features on dermal tissue

1. root hairs
2. trichomes
3. stomata

root hairs

increase the surface area for water absorption<br>no cuticle on root&nbsp;

trichomes

leaf trichomes are tiny hairs that trap water on the surface of leaves to prevent water loss&nbsp;

stoma

a stoma is a pore found in the leaf and stem epidermis that allows for gaseous exchange

stomata in epidermis

allow O2, CO2, water vapour to enter and exit the leaf&nbsp;

guard cells

contain chloroplasts for photosynthesis&nbsp;

opening and closing of guard cells determined by

turgor pressure of the 2 guard cells&nbsp;

bark

epidermis tears and dries out forming a periderm (bark)&nbsp;