Family: Asteraceae or Compositae (Sunflower family)

Distribution: cosmopolitan in distribution but abundantly occurs in tropical and temperate

region. This family consist of 1528 genera and 23,000 species

Habitat: terrestrial, wild or cultivate for ornamental and oil

Habit: annual or perennial herbs, shrubs or trees (Senecio) or rarely climber (Walkeria), twiner

(Mikania)

Roots: tap root, sometimes modified into fasiculated (Dahlia) or tuberously swollen (Helianthus

tuberosus)

Stem: aerial, stolen (Bellis), sucker (Chrysanthemum), erect, branched, cylindrical, herbaceous

or woody, solid or fistular, glabrous or pubescent, generally oil passage or latix vessel are

swollen

Leaf: cauline and ramal, alternate sometimes opposite (Helinthus annus) or whorl (Eupatorium,

Zinnia), ex-stipulate, petiolate, simple, entire or serrate, ovate, acute apex, pubescent or

glabrous, unicoasted reticulate venation, parallel venation (Corymbium)

Inflorescence: racemose, head or capitulum (Trifolium)

Flower: head consist of two types of small flowers known as florets, ray florets occur at

periphery and disc florets at centre which are surrounded by involucre of bracts

Ray floret: bracteate, sessile, zygomorphic, incomplete, unisexual, pistillate, ligulate, trimerous

or pentamerous, epigynous, various colour

Calyx: sepals are represented by small hairs or scales like structures known as pappus or

bristles, persistent, superior

Corolla: petals three or five, gamopetalous, valvate aestivation, ligulate, superior, variously

colour

Androecium: absent

Gynoecium: carpel two, bicarpellary, syncarpous, ovary inferior, unilocular with single ovule,

basal placentation, style long, stigma bifid

Fruit: simple, dry, indehiscent, cypsela

Seed: two cotyledons, ex-albuminous

Disc floret: bracteate, sessile, actinomorphic, complete, bisexual, tubular, pentamerous,

epigynous, various colour

Calyx: sepals are represented by small hairs or scales like structures known as pappus or

bristles, persistent, superior

Corolla: petals five, gamopetalous, valvate aestivation, tubular, superior, variously color

Androecium: stamens five, syngenesious, synandrous, epipetalous, anther ditheocus, basifixed,

introrse, superior

Gynoecium: carpel two, bicarpellary, syncarpous, ovary inferior, unilocular with single ovule,

basal placentation, style long, stigma bifid

Fruit: simple, dry, indehiscent, cypsela

Identifying characters

Inflorescence is head or capitulum, head consists of ray florets at periphery and disc florets at

centre surrounded by involucre of bracts

Ray florets ligulate, unisexual, pistillate, sepals are represented by pappus or bristles,

androecium absent, gynoecium – ovary inferior, unilocuar with single ovule, basal placentation,

fruit- cypsela

Disc floret: tubular, androecium syngenesious, epipetalous

Classification

Kingdom: Plantae

Division: Phanerogams

Sub-division: Angiospermae

Class: Dicotyledonae

Sub-class: Gamopetalae

Series: Inferae

Order: Asterales

Family: Asteraceae (Compositae)

Economically important plants

Artemisia vulgaris

Aster tripolium

Bidens biternate

Tagetes patula

Tagetes erecta

Chrysanthemum indicum

Eupatorium odoratum

Helianthus annus

Lactuca sativa