University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Lecture)
Unit 7: Plant Leaves
ORIGIN OF LEAVES
• Leaves arise from the activity of leaf primordia
In monocots
• At the base of the shoot apical meristem, cells interior
to the protoderm grow outward to form the leaf
primordium
• Apical meristem adjacent to primordium grow upward
to give a hood-like shape
• Tubular portion of leaf primordium continue to
DEVELOPMENT OF LEAVES surround it as sheathing leaf base
• Do not have distinct petioles
Leaf primordia • Ligules: hair-like appendages seen at the connection of
• Extends upward, farther than the shoot apical meristem the blade and leaf sheath
• Consists of protoderm, ground meristem, and • Ligulate: presence of leaf sheath
provascular tissue (primary xylem and primary phloem)
• Increases thickness
• Forms midrib and lamina (young leaf)
o Lamina: conical leaf primordium
o Meristem can form new lamina (regeneration) after
fire or grazing animals
• In compound leaves: 2 rows of loci initiate the leaflets
In dicots
• At the base of the shoot apical meristem, cells interior
to the protoderm grow outward to form the leaf FUNCTIONS OF LEAVES
primordium
• Presence of stipules in young leaves Physiological functions
o Stipules: protects the shoot apical meristem; only • Photosynthesis: flat, thin leaf (chlorenchyma cells)
predominantly seen in dicot species converts carbon dioxide and water to sugar
• Transpiration: process by which the plant loses water
o Continuous uptake of water
o Cooling effects
o Controls degree of saturation of cell with water
Economic uses
• Food: leafy greens
1|P a g e
LIANRPh
, University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Lecture)
• Herbs
o Mints from the mint family (genus mentha, family
Lamiaceae)
• Beverages: teas
• Drug uses
o Nicotiana tabacum (tobacco)
o Cannabis sativa (marijuana)
o Erythroxylum coca (cocaine)
LEAF CLASSIFICATIONS
• Insecticides
o Rotenone According to the nature of the blade
o Cymbopogon nardus (citronella)
• Simple: one blade only
• Waxes
• Compound: blade divided into leaflets or pinnae or
o Copernicia prunifera (carnauba)
pinnule
• Aromatic oils
• Medical uses Palmately compound
o Mild topical anesthetic: aloe vera
o Anticoagulant: Gingko biloba (gingko)
o Antibacterial: Syzygium cumini (duhat/Java plum)
o Antifungal: Tagetes erecta (marigold)
PARTS OF A LEAF
• Leaflets are attached to a single petiole
• Bifoliate: 2 leaflets
• Trifoliate: 3 leaflets
• Quadrifoliate/tetrafoliate: 4 leaflets
• Pentafoliate: 5 or more leaflets
Pinnately compound
• Lamina/leaf blade: flat, light- harvesting portion
• Petiole: stalk; holds the blade
o Petiolate leaf: leaf is attached to the stem by a
petiole
o Sessile leaf: leaf that is directly attached to the • Leaflets are attached to individual rachis by petiolule
stem
2|P a g e
LIANRPh
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Lecture)
Unit 7: Plant Leaves
ORIGIN OF LEAVES
• Leaves arise from the activity of leaf primordia
In monocots
• At the base of the shoot apical meristem, cells interior
to the protoderm grow outward to form the leaf
primordium
• Apical meristem adjacent to primordium grow upward
to give a hood-like shape
• Tubular portion of leaf primordium continue to
DEVELOPMENT OF LEAVES surround it as sheathing leaf base
• Do not have distinct petioles
Leaf primordia • Ligules: hair-like appendages seen at the connection of
• Extends upward, farther than the shoot apical meristem the blade and leaf sheath
• Consists of protoderm, ground meristem, and • Ligulate: presence of leaf sheath
provascular tissue (primary xylem and primary phloem)
• Increases thickness
• Forms midrib and lamina (young leaf)
o Lamina: conical leaf primordium
o Meristem can form new lamina (regeneration) after
fire or grazing animals
• In compound leaves: 2 rows of loci initiate the leaflets
In dicots
• At the base of the shoot apical meristem, cells interior
to the protoderm grow outward to form the leaf FUNCTIONS OF LEAVES
primordium
• Presence of stipules in young leaves Physiological functions
o Stipules: protects the shoot apical meristem; only • Photosynthesis: flat, thin leaf (chlorenchyma cells)
predominantly seen in dicot species converts carbon dioxide and water to sugar
• Transpiration: process by which the plant loses water
o Continuous uptake of water
o Cooling effects
o Controls degree of saturation of cell with water
Economic uses
• Food: leafy greens
1|P a g e
LIANRPh
, University of Santo Tomas
Faculty of Pharmacy, BS Pharmacy Batch 2027
PHA611: Pharmaceutical Botany with Taxonomy (Lecture)
• Herbs
o Mints from the mint family (genus mentha, family
Lamiaceae)
• Beverages: teas
• Drug uses
o Nicotiana tabacum (tobacco)
o Cannabis sativa (marijuana)
o Erythroxylum coca (cocaine)
LEAF CLASSIFICATIONS
• Insecticides
o Rotenone According to the nature of the blade
o Cymbopogon nardus (citronella)
• Simple: one blade only
• Waxes
• Compound: blade divided into leaflets or pinnae or
o Copernicia prunifera (carnauba)
pinnule
• Aromatic oils
• Medical uses Palmately compound
o Mild topical anesthetic: aloe vera
o Anticoagulant: Gingko biloba (gingko)
o Antibacterial: Syzygium cumini (duhat/Java plum)
o Antifungal: Tagetes erecta (marigold)
PARTS OF A LEAF
• Leaflets are attached to a single petiole
• Bifoliate: 2 leaflets
• Trifoliate: 3 leaflets
• Quadrifoliate/tetrafoliate: 4 leaflets
• Pentafoliate: 5 or more leaflets
Pinnately compound
• Lamina/leaf blade: flat, light- harvesting portion
• Petiole: stalk; holds the blade
o Petiolate leaf: leaf is attached to the stem by a
petiole
o Sessile leaf: leaf that is directly attached to the • Leaflets are attached to individual rachis by petiolule
stem
2|P a g e
LIANRPh
