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.
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)
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.
Tap Root, Branched, Fibrous.
The Stem of Helianthus annus is Erect, herbaceous above and woody below, cylindrical, glabrous, branched.
Cauline and ramal, exstipulate, simple, ovate, petiolate, reticulate unicostate, Leaf margin: serrate.
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.
Bracteate, sessile, incomplete, irregular, zygomorphic, ligulate, Epigynouse
Either absent or represented by 2 – 3 scales, Superior.
Yellow, gamopetalous, 2 – 5 petals, ligulate, superior.
Floral Formula K0 or scales C(2-5) A0 G(0)
Bracteate, sessile, incomplete, regular, tubular, actinomorphic, bisexual, epigynous.
Either absent or represented by 2 – 3 scales, superior.
5 petals, gamopetalous, tubular, toothed, teeth represent number of petals, superior.
5 stamens, Epipetalous, Syngenesious, Superior.
Bicarpellary, Syncarpous, Ovary: inferior and uniclocular with a single basal ovule, Placentation: basal, Stigma: bifid.
Economic importance of Family Helianthus annus (Sunflower)
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,
Flower of Carthamus yield a yellow dye
Certain species of Artemisia are used in making beer. Seeds of Centrathem are used for round worms and insecticides.
Sunflower yield oil which is used for cooking purposes.
A number of genera of the family like rag weeds and golden rods are cause of hay fever and other diseases.
Dahlias, Asters etc. Are cultivated for ornamental purposes.