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Astraceae is the largest family of angiosperms comprising of 950 Genera and approximately 20,000 species. Most common genera are Helianthus annus (sunflower), Sonchus asper (dodak), Carthamus tinctorius (kusum), Artemesia absinthium (afsantin), Lactuca sativa (salad), Ageratum conyzoides, Tagetes (gainda), Zinnia, Xanthium, etc. The members of the family are worldwide in distribution.
Family Astraceae Compositae Helianthus annus (Sunflower)
Distingushing Features Helianthus annus (sunflower)
Herb, with simple alternate leaves, flower is capitula, may be differentiated into ray and disc florets, actinomorphic or zygomorphic, epigynous, calyx represented by pappus, corolla gamopetalous of five lobes, stamen 5, epipetalous, gynoecium bicarpellary, syncarpous, ovary inferior, unilocular with a single basal ovule, fruit a cypsela.
Helianthus annus (Sunflower)
Habit
An annual herb cultivated for its seeds that yield oil rich in proteins and vitamins A, D and E. This oil is used for cooking and in salads.
Root
Tap Root, Branched, Fibrous.
Stem
The Stem of Helianthus annus is Erect, herbaceous above and woody below, cylindrical, glabrous, branched.
Leaf
Cauline and ramal, exstipulate, simple, ovate, petiolate, reticulate unicostate, Leaf margin: serrate.
Inflorescence
In Helianthus annus (sunflower) the inflorescence is Racemose A heterogamous capitulum comprising of ray and disc florets. Involucre comprising of several whorls of bracts is present at the base of the inflorescence.
Ray Florets
Bracteate, sessile, incomplete, irregular, zygomorphic, ligulate, Epigynouse
Calyx
Either absent or represented by 2 – 3 scales, Superior.
Corolla
Yellow, gamopetalous, 2 – 5 petals, ligulate, superior.
Androecium
Absent.
Gynoecium
Absent.
Floral Formula K0 or scales C(2-5) A0 G(0)
Disc Floret
Bracteate, sessile, incomplete, regular, tubular, actinomorphic, bisexual, epigynous.
Calyx
Either absent or represented by 2 – 3 scales, superior.
Corolla
5 petals, gamopetalous, tubular, toothed, teeth represent number of petals, superior.
Androecium
5 stamens, Epipetalous, Syngenesious, Superior.
Gynoecium
Bicarpellary, Syncarpous, Ovary: inferior and uniclocular with a single basal ovule, Placentation: basal, Stigma: bifid.
Floral Diagram of Helianthus annus (Sunflower)
Economic importance of Family Helianthus annus (Sunflower)
Food
Root and leaves of cichory (Cichorium intybus), leaves of Icttuce (Lactuca sativa-salad) and (Cynara cardunculus-cardoon) and roots of Jerusalem artichoke (Helianthus tuberosus) are used as food. Roots of cichory are often roasted and mixed with coffee. Similarly roots of Dandelion are also used to adulterate coffee,
Dye
Flower of Carthamus yield a yellow dye
Medicinal
Certain species of Artemisia are used in making beer. Seeds of Centrathem are used for round worms and insecticides.
Oil
Sunflower yield oil which is used for cooking purposes.
Poisons
A number of genera of the family like rag weeds and golden rods are cause of hay fever and other diseases.
Ornamental Plant
Dahlias, Asters etc. Are cultivated for ornamental purposes.