Parts of a Leaf

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Questions and Answers

What is the primary function of a leaf that differs from the stem?

To possess nodes and internodes

To absorb water and minerals

To perform photosynthesis (correct)

To produce flowers

What is the term for the stalk that connects the leaf to the stem?

Lamina

Internode

Node

Petiole (correct)

What is the part used in Senna leaf?

FLOWER

Dried leaflets of Cassia acutifolia (correct)

ROOT

STEM

What is the type of venation pattern where the veins are arranged in a parallel fashion?

Parallel Signup and view all the answers

What is the maximum amount of stalk allowed in Senna leaf?

8% Signup and view all the answers

What is the morphology of Senna leaf?

Compound paripinnate Signup and view all the answers

What is the term for the pointy tip of a leaf?

Acuminate Signup and view all the answers

What is the purpose of adding H2O2 solution in Modified Borntrager’s Test?

To oxidize the anthraquinone glycosides Signup and view all the answers

What is the type of hair that is glandular and has a unicellular head and multicellular stalk?

Unicellular head and multicellular stalk Signup and view all the answers

What is the purpose of shaking the mixture with dilute NH4OH?

To produce a red color Signup and view all the answers

What is the function of stomata in a leaf?

To regulate gas exchange Signup and view all the answers

What is the therapeutic use of Senna?

As a stimulant laxative Signup and view all the answers

What is the term for the lower epidermis of a leaf?

Epidermis Signup and view all the answers

What is the type of leaf shape that is shaped like a spatula?

Spathulate Signup and view all the answers

What are the common side effects of Senna?

Abdominal cramps and diarrhea Signup and view all the answers

What is Senna contraindicated in?

Stomach pain and inflammatory bowel disease Signup and view all the answers

What is the shape of the leaves of Cassia obovata?

Broadly obovate with tapering apex Signup and view all the answers

What is the distinguishing feature of the lower epidermis of Senna leaf?

Presence of papillosed cells Signup and view all the answers

What is the purpose of drying Digitalis leaves at a low temperature?

To preserve the cardenolides Signup and view all the answers

What is the minimum percentage of total cardenolides in Digitalis leaves?

0.3% Signup and view all the answers

What is the unit of measurement for the vein islet number?

Per square mm of the leaf surface Signup and view all the answers

What is the maximum percentage of foreign organic matters in Digitalis leaves?

2.0% Signup and view all the answers

What is the outcome of mixing residue with alcohol, NaOH, and picric acid?

An orange-red colour Signup and view all the answers

What is the approximate amount of volatile oil present in Buchu leaf?

At least 2% v/w Signup and view all the answers

What is the effect of KOH on Buchu leaf?

It gives a yellow colour Signup and view all the answers

What is the primary active constituent of Jaborandi leaf?

Alkaloids such as pilocarpine Signup and view all the answers

What is the therapeutic use of Buchu leaf?

As a diuretic and anti-inflammatory for the urinary tract Signup and view all the answers

What is the characteristic of the leaf margin of Digitalis purpurea?

Ovate, crenate margin Signup and view all the answers

What is the characteristic of the surface of Buchu leaf?

Punctate surface due to oil glands Signup and view all the answers

What is the family to which the Buchu leaf belongs?

Rutaceae Signup and view all the answers

What is the primary action of pilocarpine nitrate in ophthalmic preparations?

Contraction of the eye pupil Signup and view all the answers

What is the purpose of Hilche's test for pilocarpine?

To identify pilocarpine in a sample Signup and view all the answers

What is the active constituent of Bearberry leaf that is responsible for its therapeutic effects?

Phenolic glycosides Signup and view all the answers

What is the result of hydrolysis of arbutin with HCl?

Glucose and hydroquinone Signup and view all the answers

What is the purpose of adding FeCl3 to the filtrate in the chemical identification of Bearberry leaf?

To produce a blue colour Signup and view all the answers

What is the therapeutic use of Bearberry leaf?

As a diuretic and antiseptic in urinary tract diseases Signup and view all the answers

Study Notes

The Leaf

Definition: A lateral outgrowth on the stem, differing in structure and function from the stem, without nodes or internodes, and with lateral branches arising in its axil.
Composition: A complete leaf consists of three parts - the blade (lamina), stalk (petiole), and base.

Lamina (Leaf Blade)

Shapes: Oval, ovate, obovate, oblong, spathulate, lanceolate, cordate, reniform.
Size: Not exceeding 30 cm long.
Apex: Acuminate, emarginate, acute, macronate, round.
Margin: Dentate, ciliate.
Venation: Parallel, reticulate, pinnately reticulate, palmately reticulate.
Base: Asymmetric, symmetric, decurrent.
Surface: Smooth, punctate, glabrous, pubescent.

Structure of the Lamina

Cuticle
Epidermis (Stomata)
Palisade
Spongy mesophyll
Cortical tissue

Trichomes (Hairs)

Non-glandular hairs: Unicellular, multicellular, unbranched, branched, T-shaped, twin, stellate.
Glandular hairs: Unicellular head & unicellular stalk, unicellular head & multicellular stalk, bicellular head & multicellular stalk, multicellular head & unicellular stalk, multicellular head & multicellular stalk.

Stomata

Osteole
Guard cells
Subsidiary cells
Types: Diacytic, paracytic, anomocytic, anisocytic.

Senna Leaf

Definition: Dried leaflets of Cassia acutifolia or Cassia angustifolia (Family Leguminosae).
Morphology: Compound paripinnate, entire margin.
Microscopical identification: With phloroglucin + conc. HCl.
Active constituents:
- Anthraquinone glycosides (sennosides A, B, C, D).
- Flavonoids (kaempferol, isorhamnetin).
- Mucilage.
Therapeutic uses: Stimulant laxative.
Chemical identification: Modified Borntrager’s Test.

Digitalis Leaf

Definition: Dried leaves of Digitalis purpurea (Family Scrophulariaceae).
Active constituents:
- Cardenolides (digitoxin).
Therapeutic uses: Digitalis is used in treatment of cardiac failure and atrial fibrillation.
Chemical identification: H2SO4, a reddish-brown ring is obtained between the two layers.
Allied drugs: Digitalis lanata, Digitalis lutea.

Buchu Leaf

Definition: Dried leaves of Barosma betulina (Family Rutaceae).
Morphology: Rhomboid lamina, punctate surface.
Active constituents:
- Volatile oil (30% diosphenol).
- Flavone glycoside (diosmine).
Therapeutic uses: Disinfectant, diuretic, and diaphoretic action.
Chemical identification: + KOH gives a yellow colour.

Jaborandi Leaf

Definition: Dry leaflets of Pilocarpus microphyllus, P. jaborandi, and P. pinnatifolius (Family Rutaceae).
Morphology: Compound leaf, imparipinnate, punctate surface.
Active constituents:
- Alkaloids (pilocarpine, isopilocarpine, pilosine, isopilosine).
- Volatile oil.
Therapeutic uses: Pilocarpine is antagonistic to atropine, used in ophthalmic preparations (contraction of the eye pupil = myotic).
Chemical identification: Hilche’s test: (for pilocarpine).

Bearberry Leaf (Uva-ursi)

Definition: Dried leaves of Arctostaphylos uva-ursi (Family Ericaceae).
Morphology: Simple, obovate, rounded apex, entire margin.
Active constituents:
- Phenolic glycosides (arbutin and ericolin).
- Tannins (gallic and ellagic acid).
Therapeutic uses: Diuretic and antiseptic in urinary tract diseases.
Chemical identification:
- Powder + dil. HCl, heat gently crystalline sublimate of hydroquinone on the slide.
- Powder + water, boil, filter, add drops of FeCl3 to the filtrate blue colour.

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Description

Understand the structure and function of a leaf, including its components and types. Learn about the blade, stalk, and base of a leaf, and how they differ from each other.