The Flowers: Structure and Importance

Flowers

• A flower is a compressed fertile shoot crowded with modified leaves (floral leaves) that is adapted for the production of seeds and fruits.
• It is very important for the identification of unknown plants.
• A typical complete flower consists of four organs:
• Calyx: composed of sepals
• Corolla: composed of petals
• Androecium: composed of stamens
• Gynaecium: composed of carpels
• The receptacle is the swollen or expanded apex of the flower stalk, which can be short or elongated.
• Flowers may be aggregated on the plant forming inflorescence, which can be classified as Cymose or Racemose based on the branching method.
• Bracts and bracteoles are accessory leafy structures that may be present in flowers.
• Flowers can be classified as:
• Hermaphrodite (bisexual): having both male and female organs
• Unisexual: having one sexual organ
• Sterile: having no sexual organs

Clove

• Origin: dried flower-buds of Eugenia aromatica (E.caryophyllata) from the Myrtaceae family.
• Geographical source: Zanzibar, Indonesia, Madagascar, and Brazil.
• Description: dry flower-buds with a strong, spicy, and aromatic odor and taste, reddish-brown in color, and 16-21 mm long.
• Calyx: four, thick, acute-triangular sepals.
• Corolla: four unexpanded petals.
• Powdered clove: brown in color, with strong spicy taste and slight characteristic aromatic odor, and pungent numbness.
• Microscopic characteristics: numerous triangular pollen grains, fragments of parenchymatous tissue showing entire or broken oil gland, and schizolysigenous oil gland.
• Active constituents: 15-20% volatile oil (Eugenol, acetyl eugenol, sesquiterpenes), and 10-13% tannin.
• Uses: treatment of teeth pain, carminative, antispasmodic, preparation of vanillin, preparation of clove oil, antiseptic, antihistaminic, and anticarcinogenic compound.
• Adulteration: clove stalk, mother clove, and exhausted clove.
• Chemical tests: test for Eugenol, and test for tannins.

Hibiscus

• Origin: dried calyx and epicalyx of the flower of Hibiscus sabdariffa from the Malvaceae family.
• Geographical source: South of Egypt, Sudan.
• Description: dried curved pieces of calyx and epicalyx, purplish to crimson in color, with a characteristic odor and slightly acidic and mucilaginous taste.
• Microscopic characteristics: stellate hairs, cottony non-glandular hairs, polygonal tabular cells, lignified fibers, and spiral vessels.
• Active constituents: organic acids (citric, malic, hibiscic), colouring matter of anthocyanins (hibiscin), flavonoid (hibiscetin), and large amount of mucilage.
• Uses: antihypertensive, sedative, digestive, soft drink, emollient, substituent for tea and coffee, and weight reducing agent.
• Chemical identification: boiling powdered Hibiscus flower in HCI and filtering, followed by addition of sodium acetate solution and conc. NH4 OH to produce violet and green colors, respectively.