L5: Dermal Tissue System Flashcards
3 stages of cell growth
Cell division
Cell expansion
Cell differentiation
epidermis
covers the surface of all plant organs (produced by primary growth)
Diverse epidermal cell types
pavement cells
guard cells
trichomes
root hairs
Dermal tissue system
Outermost layer of cells that controls what goes in and what goes out and protects it from the environment
What is the dermal tissue system often covered by?
covered by a waxy, hydrophobic cuticle
Function of the plant cuticle
minimize water loss and prevent organ fusion
surface self-cleaning
What is the plant cuticle lotus effect?
Hydrophobic cuticle allows water droplets to bead on the plant’s surface and assists in removing debris (self cleaning)
Hypothesized function of the plant cuticle’s cuticular folds and ridges
prevent extended contact between different surfaces
create iridescence that attracts pollinators
help bugs attach, walk, and even guide towards desired features of the plant
periderm is the _________ epidermis
secondary
pavement epidermal cells
general protection and support
typically no chloroplasts (no photosynthesis)
guard cells
2 guard cells together that form pores in the plant’s epidermis that can open and close by turgor pressure
Guard cells function
control gas exchange
Where are guard cells most abundant
the bottom of a leaf
What are guard cells often flanked by to help regulate turgor
subsidiary cells
turgid (guard cells)
open
flaccid (guard cells)
closed
specialized features of the guard cell
thickened inner wall lining the pore/aperture
cellulose microfibrils are radially oriented
Trichome
a unicellular or multicellular outgrowth of the epidermis on stems, leaves, or flowers
Trichome functions
protection
limit water loss
protect from high sunlight by reflecting it
exude chemicals for defense or attraction
non-glandular/non-secretory trichomes
often hair-like or spike-like trichomes that provide physical protection
glandular/secretory trichomes
bulbous trichomes that produce secretions/oils that provide chemical protection
2 root epidermal cell types
Hair cells (trichoblasts)
Non-hair cells (atrichoblasts)
Hair cells (trichoblasts) function
absorb water and nutrients
Non-hair cells (atrichoblasts) function
provide support and ensure space between hairs
types of primary meristems
protoderm
ground meristem
procambium
type of apical meristems
shoot and root
secondary (lateral) meristems
vascular cambium
cork cambium
periderm
the secondary epidermis that is derived from the secondary meristem called cork cambium
periderm function
protection and control of water loss
