Laboratory notes on plant tissues. Subtopics include classifications of tissues according to the stage of development, composition, origin, location, and function, detailed notes on dermal tissue composition and function, simple permanent ground tissues, and complex permanent ground tissues.
University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
Exercise 6: Plant Tissues • First derivative of promeristem
• Retains meristematic properties of continuous division
Vascular plant tissue: derived from the product of fertilized egg
• Situated at the tips of the root, stem, and appendages
(zygote) that has undergone repeated cell division
• Cells divide repeatedly, develop and mature to form
primary permanent tissues that make the primary
Tissues
structure/plant body
•
Meristematic Permanent
tissues tissues E.g. apical meristem at the root and shoot apex
Origin &
Location Simple Complex
development
Primary
Secondary meristem
Promeristem Apical Intercalary Parenchyma Collenchyma Xylem Phloem
• Gives rise to secondary tissue for plants exhibiting
meristem
Secondary
meristem
Lateral Sclerenchyma
secondary growth
Function • E.g. lateral and intercalary meristems, vascular and
Protoderm Procambium
cork cambium
Ground
meristem
Classification based on position (location)
TISSUES Apical meristem
• Group of cells performing a specific function • Cells can differentiate into various cell types
• Gives rise to primary tissues to form primary plant body
Classification based on stage of development • Growth region in root tips, tips of new shoots and leaves
Embryonic/meristematic Intercalary meristem
• Undifferentiated cells • Associated with growth, length, and elongation
• Meristematic: actively dividing cells; in mitotic state • Situated in the stem, base of nodes, and leaf plates
• Capable of rapid growth and regrowth
Permanent • E.g. intercalary tissue at base of blade of grass allows it
• Mature, differentiated cells to regrow after being cut
Classification based on composition Lateral meristem
• To grow in diameter
Simple
• To increase girth or thickness as part of secondary
• One type of cells
growth
• E.g. vascular cambium, cork cambium
Complex
• Different types of cells
Classification based on initiating cells (origin)
Promeristem (primordial meristem)
• Group of young cells of a growing organ
• Occupies a small area at the tip of the stem and root
• Further divides to form primary meristem
Primary meristem
Classification based on function
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LIANRPh
, University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Laboratory)
Protoderm meristem (dermatogen) • E.g. cotton trichomes can be made into threads to
• Develops to form dermal tissue system (epidermis) weave cloth
Procambium (plerome) Glandular/secretory trichomes
• Gives rise to vascular tissue system (xylem, phloem)
Fundamental/ground (periblem)
• Gives rise to ground tissue system that forms
hypodermis, cortex, and pith
DERMAL TISSUE (EPIDERMIS)
• Outermost surface of herbaceous stem, leaf, and root
Non-glandular trichomes
• For protection
• Regulates the exchange of materials
Stinging
• Irregular, isodiametric, distinctly elongated
• Encrusted with cutin
o Cuticle layer of plants prevents water loss and plant
dehydration
o Cutin inhibits CO2 entry for photosynthesis
o Guard cell pairs with stomatal pore between cutin to
permit CO2 entry
o Stomatal pores are open during daytime for
photosynthesis Bristle
Accessory cells
• Reservoir of water and ions
Bulliform cells (motor cells)
• Longitudinal rows of vacuolated cells
• Large, bubble-shaped, may be white or colorless
• Found on top surface of leaves (midvein) in groups of
Scale
multiple monocots
• Prevents water loss via transpiration
Epidermal hairs/trichomes
• Elongation of epidermal cells outwards
• Increases surface area of roots for higher water
absorption
• Aids in nutrient uptake
• For protection against insects and excessive sunlight Stellate
o Thorn-like structures can be defensive structures
• Secretory gland for salt, antiherbivore compounds
• Spread of seeds
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LIANRPh
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