University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
Exercise 8: Plant Roots • Single prominent root
PRIMARY FUNCTIONS Lateral or branch roots
• Anchorage
• Smaller and arise from the taproot
• Absorption of water and nutrients
• Hormone production (cytokinin, gibberellin) for plant Root hairs
growth and development • Arise from the epidermis
• Secondary functions designated to specific root • Single-celled extensions that increase absorptive area
systems
• No line of demarcation in the epidermal cells
o Food storage
• Transitory: dies within 4-5 days
o Support
o Protection Root tip
• Growing portion protected by the root cap
TYPES OF ROOT SYSTEMS
• Pushes through the soil
Taproot • Region of length growth
• Single prominent root with smaller lateral/branch roots
L-SECTION OF ROOT
• Common in dicot species and gymnosperms
• Secondary growth Zone of division/apical meristem
• E.g. fleshy taproot: carrots, beets, radish; swollen
• Continuation of root cap
lateral roots: sweet potato, cassava
Quiescent center
Fibrous
• Mitotically inactive region
• Similarly sized roots • Reserve of healthy cells
• No prominent enlarged primary root • Resistant to toxic substances and radiation
• Common in monocot species
• For absorption Zone of elongation
• Delicate, hair-like • Newly formed cells begin to increase in length;
lengthening the root
Adventitious
• Cells are older than cells in zone of cell division
• Not arise from preexisting root • Cells start to differentiate but no maturation occurs
• Usually used in increasing absorption area
• Common in both monocot and dicot species Zone of maturation
• Root cells begin to differentiate into special cell types
Brace root
• Transfer of minerals from epidermis to the vascular
• Arise from main trunk stem bundle
• E.g. corn • Root hairs start to develop
Prop root
INTERNAL ANATOMY OF DICOT ROOT
• Arise from lateral branches
STRUCTURE OF ROOTS
Taproot
1|P a g e
LIANRPh
, University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
• Checkpoint for materials entering the root’s vascular
system
• Thick-walled cells encrusted with suberin and lignin
• Diffusion is inhibited
• Appears first before root hairs
Passage cells
• Cells without the Casparian strip
• Thin-walled to allow apoplastic transport
Protostele: xylem and phloem of the stele are arranged Casparian strip
alternately in an X shape • Waxy region composed of suberin and lignin in
endodermal cell walls
Dermal region • Forces water and solutes to cross the plasma
• Epidermis with root hairs membranes instead of intercellular spaces
• Ensures toxic substances and pathogens do not enter
Cortex the root
• Outer collenchyma
• Middle parenchyma
• Inner endodermis
Stele/vascular cylinder
Pericycle
• Outermost layer
• Arise from procambium
• Produces cork cambium and lateral roots VARIATIONS IN NUMBER OF XYLEM STRANDS
• Between endodermis and vascular cells
Triarch
Primary xylem • 3 xylem poles
• Central large cells • Eudicot
• Protostele
Primary phloem
• Narrow cells at tips of arms Tetrarch
• 4 xylem poles
Vascular cambium • Eudicot
• Arise from procambium and pericycle • Protostele
• Produces secondary xylem and secondary phloem
Pentarch
Endodermis • 5 xylem poles
• Borders the stele • Eudicot
• Innermost layer of the cortex • Protostele
• Exclusive to roots
Polyarch
2|P a g e
LIANRPh
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
Exercise 8: Plant Roots • Single prominent root
PRIMARY FUNCTIONS Lateral or branch roots
• Anchorage
• Smaller and arise from the taproot
• Absorption of water and nutrients
• Hormone production (cytokinin, gibberellin) for plant Root hairs
growth and development • Arise from the epidermis
• Secondary functions designated to specific root • Single-celled extensions that increase absorptive area
systems
• No line of demarcation in the epidermal cells
o Food storage
• Transitory: dies within 4-5 days
o Support
o Protection Root tip
• Growing portion protected by the root cap
TYPES OF ROOT SYSTEMS
• Pushes through the soil
Taproot • Region of length growth
• Single prominent root with smaller lateral/branch roots
L-SECTION OF ROOT
• Common in dicot species and gymnosperms
• Secondary growth Zone of division/apical meristem
• E.g. fleshy taproot: carrots, beets, radish; swollen
• Continuation of root cap
lateral roots: sweet potato, cassava
Quiescent center
Fibrous
• Mitotically inactive region
• Similarly sized roots • Reserve of healthy cells
• No prominent enlarged primary root • Resistant to toxic substances and radiation
• Common in monocot species
• For absorption Zone of elongation
• Delicate, hair-like • Newly formed cells begin to increase in length;
lengthening the root
Adventitious
• Cells are older than cells in zone of cell division
• Not arise from preexisting root • Cells start to differentiate but no maturation occurs
• Usually used in increasing absorption area
• Common in both monocot and dicot species Zone of maturation
• Root cells begin to differentiate into special cell types
Brace root
• Transfer of minerals from epidermis to the vascular
• Arise from main trunk stem bundle
• E.g. corn • Root hairs start to develop
Prop root
INTERNAL ANATOMY OF DICOT ROOT
• Arise from lateral branches
STRUCTURE OF ROOTS
Taproot
1|P a g e
LIANRPh
, University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
• Checkpoint for materials entering the root’s vascular
system
• Thick-walled cells encrusted with suberin and lignin
• Diffusion is inhibited
• Appears first before root hairs
Passage cells
• Cells without the Casparian strip
• Thin-walled to allow apoplastic transport
Protostele: xylem and phloem of the stele are arranged Casparian strip
alternately in an X shape • Waxy region composed of suberin and lignin in
endodermal cell walls
Dermal region • Forces water and solutes to cross the plasma
• Epidermis with root hairs membranes instead of intercellular spaces
• Ensures toxic substances and pathogens do not enter
Cortex the root
• Outer collenchyma
• Middle parenchyma
• Inner endodermis
Stele/vascular cylinder
Pericycle
• Outermost layer
• Arise from procambium
• Produces cork cambium and lateral roots VARIATIONS IN NUMBER OF XYLEM STRANDS
• Between endodermis and vascular cells
Triarch
Primary xylem • 3 xylem poles
• Central large cells • Eudicot
• Protostele
Primary phloem
• Narrow cells at tips of arms Tetrarch
• 4 xylem poles
Vascular cambium • Eudicot
• Arise from procambium and pericycle • Protostele
• Produces secondary xylem and secondary phloem
Pentarch
Endodermis • 5 xylem poles
• Borders the stele • Eudicot
• Innermost layer of the cortex • Protostele
• Exclusive to roots
Polyarch
2|P a g e
LIANRPh
