Pharmacognosy I - Lecture 4

Pharmacognosy I - Lecture 4

• Lecture delivered by Ahmed Elbermawi, PhD
• Focuses on plant anatomy
• Covers stomata types (images provided for student identification)
• Covers vascular bundle types (images provided for student identification)
• Discusses primary and secondary plant growth
• Describes the anatomy of primary plant organs (leaves, stems, and roots)

Stomata

• Question presented to students (images)
• Identification of different stomata types is required
• No further details given

Vascular Bundles

• Question presented to students (images)
• Identification of vascular bundle types is required
• No further details given

Plant Anatomy

• Diagram shows primary plant organs (leaves, stems, and roots) with labeling.
• Leaves - Photosynthetic system.
• Stems - Support plant structure, transport nutrients, defending against diseases and predators.
• Roots - Absorption of water and nutrients, anchoring plant in ground, protection from soil bacteria and fungi.
• Primary growth - Increases plant length from tips (root and shoots).
• Secondary growth - Increases plant width or girth from lateral meristems (vascular and cork cambium).

Root Anatomy

• Root structure comprises vascular cylinder (stele), ground tissue (cortex), and epidermis (piliferous layer).
• Root hairs - Increase surface area for absorption, essential for growth and development
• Root cap - Protects the apical meristem during growth

Leaf Anatomy

• Leaf structure organization - different in various parts (midrib, lamina)
• Epidermis - Single layer on upper and lower surfaces with trichomes and stomata.
• Ground tissue - Upper to Lower surfaces - composed of palisade mesophyll and spongy mesophyll.
• Vascular tissue - composed of xylem (located above phloem)
• Protoxylem - directs towards the upper epidermis.

Stem Anatomy

• Dicot stem - Epidermis, a single ring of vascular bundles V.B. arranged in ring around central region pith, Cortex, Pith, pericycle, endodermis, well-marked, hypodermis almost collenchyma
• Monocot stem - V.B. are scattered irregularly throughout, narrower than dicot stems, Cortex, Pith, pericycle, endodermis are indistinguishable, hypodermis almost sclerenchyma

Dicot vs. Monocot Comparison

• Dicot and monocot root/stem and leaf anatomy comparison (table provided).
• Key differences in structure and arrangement of vascular bundles (V.B)
• Additional features covered include stomata type, epidermis, pith , palisade and sponge mesophyll and overall types/structures

Quiz Questions

• Question on sclereids (location in plant tissue)
• Question on parenchyma function
• Question on tracheids vs. fibers
• Question on dicot stem hypodermis
• Various multiple-choice questions regarding plant tissue types/functions, root/stem/leaf differences, etc., providing further study material.