6. Compositae (Asteraceae) [Notes]

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Morphology of Flowering Plants

Compositae (Asteraceae)

Systematic Position

• Domain: Eukarya
• Kingdom: Plantae
• Division: Angiospermae
• Class: Dicotyledonae
• Order: Astarales
• Family: Compositae (Asteraceae)

General Information

• Common Name: Sunflower family
• Description: Largest family of angiosperms with the most genera and species.
• Evolutionary Status: Most advanced among angiosperms.

Vegetative Characters

• Habit: Herbs, shrubs, or rarely trees
• Root: Tap root system
• Stem: Usually herbaceous, erect, branched, solid
• Leaves: Mostly alternate, exstipulate, simple pinnately or palmately or compound with reticulate venation

Floral Characters

• Inflorescence: Capitulum or head
• Flower: Epigynous, usually pentamerous, bisexual or unisexual, actinomorphic or zygomorphic, bracteate or ebracteate

Ray Florets

• Type: Unisexual, zygomorphic
• Calyx: Pappus or scaly, persistent
• Corolla: Petals 5, gamopetalous
• Androecium: Absent
• Gynoecium: Bicarpellary, syncarpous, ovary inferior, unilocular, basal placentation
• Floral Formula: Br.% K(papus) C(5) Ao G(2)

Disc Florets

• Type: Bisexual, actinomorphic
• Calyx: Pappus
• Corolla: Petals 5, gamopetalous
• Androecium: 5 stamens, epipetalous, syngenesious, dithectus
• Gynoecium: Bicarpellary, syncarpous, ovary inferior, unilocular, basal placentation
• Fruit: Cypsella
• Seed: Non-endospermic
• Floral Formula: K(pappus) C(5) A5 G(2)

Economic Importance

• Sunflower (Helianthus annuus): Ornamental and source of unsaturated edible oil.
• Marigold (Tagetus erectus)
• Carrot Grass or Congress Grass (Parthenium): Weed growing in all parts of India.
• Chrysanthemum: Pyrethrum, a commercial insecticide, is obtained from its inflorescence.
• Carthamus tinctorius: Red dye for dyeing silk and edible oil from seeds.
• Artemisia annua: Santonin drug from the flower used to remove worms from the body.