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Systematic Position
Division: AngiospermaeClass: Dicotyledonae
Subclass: GamopetalaeSeries: Inferae
Order: AsteralesFamily: Asteraceae (=compositae)
Commonly known as sunflower family. It is the largest family in dicots. It includes about 900 genera and 13,000 species. It has a cosmopolitan distribution. There are around 100 species in India.Characteristic Features
- Habit: Mostly annual herbs, rarely shrubs and trees.
- Root: Taproot system, branched.
- Stem: Herbaceous or woody, erect, branched.
- Leaves: Simple, alternate or opposite, exstipulate, petiolate, hairy, reticulate venation.
- Inflorescence: Head or capitulum, terminal or axillary. Florets surrounded by an involucre of bracts.
- Flower: Bisexual, pentamerous, heterochlamydeous, epigynous.
- Ray florets: Towards periphery, sessile, bracteate, pistillate or neutral, zygomorphic, ligulate.
- Calyx: Absent or hairy pappus, or scaly persistent.
- Corolla: Petals 5, polypetalous, ligulate.
- Androecium: Absent.
- Gynoecium: Bicarpellary, syncarpous, unilocular, one ovule, the locule, basal placentation, style narrow, stigma branched, ovary inferior.
- Disc Florets: Towards the centre, bracteate, bisexual, actinomorphic, tubular, epigynous.
- Calyx: Absent or modified into pappus.
- Corolla: Sepals 5, Gamosepalous, tubular.
- Androecium: Stamens 2, epipetalous, syngenesious dithecous.
- Gynoecium: Bicarpellary, Syncarpous, unilocular, one ovule, on basal placentation style single, stigma bifid.
- Neutral florets: Both androecium and gynoecium are absent. Remaining characters similar.
- Fruit: Cypsela.
- Seed: Non-endospermic.
- Floral formula:
Ray florets
Disc florets
Neutral florets
fig. 27.39 Types of florets, their L.S. floral parts, floral diagram and floral formula
Common Examples
Edible
1. Lactuca sativa (Lettuce)
2. Elephantopus - Leaves edible3. Helianthus tuberosum - tubers edible, seeds yield oil
Medicinal
1. Carathamus tinctorius - Oil used for treating injuries
2. Cynara scolymus - flowers are used for treating diabetes3. Artinesia obisynthium - yields santonin used for treating worms
4. Xanthium stramonium - leaves used for treating tooth acheOrnamental
1. Helianthus annus sunflower yields oil
2. Tagetus erectus - marigold3. Chrysanthemum species
4. Cosmos species5. Veronica species
6. Zinnia species



