Distribution:
this family contains about 900 genera and 13000 species. in India family is represented by 138 genera and about 708 species. Example: (sunflower) Helianthus annuus .
Vegetative Character:
Habit: mostly annual or perennial herb rarely under shrub.
Root: tap root system, sometime roots get swollen due to storage of food. Example: dahlia
Stem: mostly herbaceous, sometime rigid or with swollen nodes.
Leaves: mostly simple and alternate sometime in some plant crowded opposite leaf also present.
Reproductive Parts:
Inflorescence: inflorescence is racemose , head and capitulum.
Flower: flower are called florets. they are of two types
ray florets and disc florets
in some cases the ray and disc florets are bisexual.
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Calyx: calyx is sometime absent or represented by five lobed at the top of the ovary.
usually it is represented by pappus or hair like structure .
Corolla: consists of five fused petals. it may be ligulate. the aestivation is valvate.
Androecium: it is absent in ray floret but in disc floret it is present five in number. epipetalous.
Gynoecium: bicarpellary, syncarpous, inferior ovary, unilocular with single ovule.
Fruits and Seeds: seeds are non endospermic and embryo is straight.
Pollination and Dispersal: mostly pollination is done by large variety of insects. but some fruits at pappus condition are adapted by wind dispersal.
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