Pharmacognosy 2 - Week 1 Quiz

Pharmacognosy 2 (PHG 203) - Week 1

• Course name: Pharmacognosy 2
• Course code: PHG 203
• Week number: 1
• Instructor: Dr. Heba

Intended Learning Outcomes (ILOs)

• a1: Understand the fundamental concepts of pharmacognosy, focusing on the morphological, histological, and taxonomic aspects of important plant organs (fruits, herbs, and subterranean parts).
• d1: Master the specialized terminology used in discussions of plant-based medicine. Express information precisely with clear details.
• d2: Develop the skill to create accurate scientific drawings of the studied plant components.

Definition of Fruit

• A fruit is a plant structure that develops from the fertilized ovary (gynoecium) of a flower.
• Its primary function is protecting and providing nourishment to the developing seeds.
• The pericarp (fruit wall) exhibits two scars: one at the base and another at the apex.

Origin of the Fruit

• The fruit forms as a result of fertilization, pollen tube growth, and zygote development.
• Diagram illustrating the process of fruit formation from the flower to the seed.

Fruit Classification

• Fruits are categorized into True, False, and Composite fruits.
  • True fruit: Develops solely from the flower's ovary.
  • False fruit: Involves other parts of the flower in its development, in addition to the ovary.
  • Composite fruit: Forms from a whole inflorescence rather than a single flower.

Subtypes of Fruits

• True fruits can further be divided into Simple, Aggregate, and Multiple fruits.
  • Simple fruits: Originated from a single carpel or several fused carpels (syncarpous).
  • Aggregate fruits: Develop from multiple separate carpels (apocarpous).
  • Multiple fruits: Formed from multiple flowers in an inflorescence.

Dry Dehiscent Fruits

• Characteristics: The fruit wall dries out and eventually splits open (dehisces) to release seeds. Different types exist.
  • Follicle: A single-carpel fruit dehiscing along the ventral suture.
  • Legume: A single-carpel fruit dehiscing along both ventral and dorsal sutures.
  • Capsule: A multiple carpel fruit, dehiscing through valves, pores, or a lid.
  • Silique: A two-carpel fruit dehiscing along a central partition (septum).

Dry Indehiscent Fruits

• Characteristics: Remain closed after ripening, and do not open to release the seeds.
  • Achene: A single-seeded fruit with a free pericarp from the seed coat.
  • Caryopsis (Grain): A modified achene in which the pericarp is fused with the seed coat.
  • Cypsela: A single-seeded fruit with a slightly hardened pericarp, free from the seed, and often arising from an inferior ovary.
  • Samara: A winged fruit that aids seed dispersal.
  • Nut: A one-seeded fruit with a hardened pericarp.

Schizocarpic Fruits

• Characteristics: The fruit splits into several one-seeded segments after ripening.
  • Cremocarp: A two-carpelled fruit, splitting longitudinally into two mericarps, with a forked carpophore.

Succulent Fruits

• Characteristics: Possess fleshy tissues within the fruit wall.
  • Drupe: Epicarp (skin), mesocarp (fleshy pulp), and endocarp (stone).
  • Berry: Entire fruit wall is fleshy.
  • Pepo: Hard or leathery epicarp (skin).
  • Hesperidium: Thin epicarp, pithy mesocarp, and a membranous endocarp, usually with juice sacs (e.g., citrus fruits).

Aggregate Fruits

• Fruits formed from multiple separate carpels of one flower, joined to a common receptacle.
• Examples: Strawberry (achenes on a fleshy receptacle), and star anise.

False Fruits

• Fruits that develop from other parts of the flower or the receptacle in addition to the ovary.
• Examples: Apples and pears (the fleshy part arises from the receptacle).

Composite Fruits

• Fruits formed by the combination of several individual flowers in an inflorescence.
  • Strobile (Cone): Dry, scaly fruit, formed from an inflorescence.
  • Sorosis: Multiple fruitlets, fused together.
  • Syconus: Hollow receptacle containing numerous fruits (e.g., fig).

Structure of the Fruit

• Pericarp: The outer wall of the fruit, consisting of three parts:
  • Epicarp: Outermost layer (skin).
  • Mesocarp: Middle layer (pulp, if present).
  • Endocarp: Innermost layer (stone or membrane surrounding the seed).

General Characteristics of Umbelliferous Fruits

• Morphological: True, simple, dry schizocarpic cremocarp that splits into two mericarps. Fruits are derived from an inferior ovary. Characterised by primary ridges.
• Histological (Detailed Study): Describes the internal tissue structures (epidermis, mesocarp containing ducts and oils (vittae), vascular bundles, endocarp cells arrangement)

Secretory Tissues in Fruits

• The various methods of secretion by specialized tissues in plants, including glands, hairs, ducts, and vessels.