Asteraceae (Compositae) Floral formula , characters & importance

(ASTERACEAE (COMPOSITAE) Sunflower Family)

Diagnostic characters

1. Habit: Annual or perennial herbs or small shrubs or small tree or climbers.
2. Roots: Fibrous tap root
3. Stein: Herbaceous; spiny or without spines; cylindrical, hairy.
4. Leaves: Petiolate; alternate or opposite; simple; exstiputate;
5. Inflorescence: Capitulum surrounded at the bases by a group of involucres. The receptacle is flat. The flowers in the receptacles are florets. There are two types of florets:
   • Homogamous: In this case, all flowers are of same kind.
   • Heterogamous: In this case, two types of flowers are present in the capitula. Example: Sunflower. Sunflower has two types of small flowers, disc florets and ray florets. The disc florets are present in the central region. They are tubular and bisexual. The ray florets are present towards the periphery. They are pistillate or neuter.

   6. Flower: Sessile; ebracteate: aetinomorphic or zygomorphic: pentamerous Regular or irregular; complete or incomplete; unisexual Or hermaphrodite; epigynous;
   7. Calyx: .Poorly developed; generally represented by ring of 5 small teeth. They may be present in the form of small scales or hairs or bristles.
   8. Corolla: Gamopetalous; tubular with 5-5 lobed or ligulate with 3-4 teeth. Sometimes bilabiate;
   9. Stamens: 5 stamens rarely 4; epipetalous; syngenesious (filament free anther united); formitig a tube which encloses style.
   10. Carpel: Bicarpellary; syncarpous; stigma bind ovary inferior; placentation basal.
   It Fruits: Achenial one seeded cypselM
   12. Seed: non-endospermic seed.

Floral formula and floral

Economic Importance

1. Food: Some plants of this family are used as food Sonic of these are lettuce (fsi.–), roots and leaves of cichory.
2. Medicinal: Artemisia yields a drug santonine. It is useful for round worms. Lettuce has properties resemble to opium (_rill.
3. Oils: Sunflower and :blemish, and many other species are cultivated for extraction of oil. This oil is used as cooking oil.
4. Dyes: The flowers of C’arlharints linclorhis yield a yellow dye.
5. Insecticide: The flowers of Cluysamhemum (_Lop jf) are grounded to produce a powder. It has insecticide called Pyrethrum.
6. Poisons: A large number of members of this family like rag weeds and golden rods cause hay fever. Certain plants are poisonous to livestock.
7. Ornamental plants: Many members of this family are cultivated as ornamental plants. These are sunflower. Chrysanthemum, Zinnia etc.
8. Weeds: Some plants acts as weeds like Sonchus.

Distribution pattern

It is the largest family of Angiosperms. It has more than 1000 genera and 93000 species. ft is distribute all parts of the world.

Common species

•  Helianthus annuus (sunflower )
• Lactuca saliva (Lettuce )
• Sonchus asper
• Chrysanthemums indicus