Botanical description and Economic importance of Tridax procumbens

Botanical description of Tridax procumbens

Habit

A decumbent herb. Stem and leaves are covered by hairs.

Root

Tap root system.

Stem

Herbaceous, cylindrical, decumbent and branched.

Leaf

Simple, opposite, exstipulate and margins dentate showing reticulate venation.

Inflorescence

A terminal heterogamous head and receptacle of the head is convex and surrounded by green involucre. The tubular florets occupy the centre and the ligulate florets are found at the margins.

Tubular or disc florets

Bracteate, ebracteolate, sessile, complete, bisexual, pentamerous, actinomorphic and epigynous.

Calyx

Reduced into numerous hairy outgrowths called pappus arranged on top of ovary and persistent.

Corolla

Petals 5, gamopetalous, regular, tubular and showing valvate aestivation.

Androecium

Stamens 5, epipetalous, syngenesious and alternate with petals. Anthers are dithecous, basifixed, introrse and dehiscing longitudinally.

Gynoecium

Ovary inferior, bicarpellary and syncarpous. Ovary unilocular with a single ovule on basal placentation. Style simple with bifid stigma.

Fruit

A cypsela.

Seed

Non-endospermous.

Ligulate or ray florets

Bracteate, ebracteolate, sessile, incomplete, pistillate, zygomorphic and epigynous.

Calyx

Reduced into numerous hairy outgrowths called pappus arranged on top of the ovary and persistent.

Corolla

Petals 5, gamopetalous, irregular, ligulate or bilabiate, the anterior lip is large and 3 lobed, the posterior one is small in the form of 2 teeth like projections showing valvate aestivation.

Androecium

Absent.

Gynoecium

Ovary inferior, bicarpellary and syncarpous. Ovary unilocular with a single ovule on basal placentation. Style simple with bifid stigma.

Fruit

A cypsela.

Seed

Non-endospermous.

Floral formula

Br., Ebrl.,%,  , K x , C(5), A0, G (2)

Economic importance

1.        Oil plants

Oil extracted from the seeds of Helianthus annuus (sunflower) is edible and used as a cooking medium. Oil extracted from the seeds of

Carthamus tinctorius (safflower) is edible and also used in the manufacture of soap. It contains less amount of cholesterol and therefore it is recommended for heart patients.

2.        Medicinal plants

The entire plant, Eclipta prostrata (Karisalankanni) is used in the preparation of bathing oil and also in the treatment of jaundice, spleen and liver disorders. The drug santonin obtained from the heads of Artemesia maritima is used for expelling intestinal round worms.

3.        Dye plants

A natural red dye obtained from Carthamus tinctorius is used for dyeing silks. A yellow dye obtained from the flowers of Tagetus erecta is used for dyeing cotton.

4.        Pesticides

A dried powder called 'Pyrethrum' obtained from the flower heads of Chrysanthemum cinerarifolium and C. coccineum is used as mosquito repellant.

5.        Beverage

Powder obtained from the seeds of Cichorium intybus (chicory/ kasini keerai) is mixed with coffee powder. Leaves are used to treat several diseases and also used as salad.

6.        Ornamental plants

Helianthus annuus (sunflower), Tagetus petula (French marigold),

Calendula officinalis (pot marigold) and Zinnia elegans are grown in gardens for their beautiful flowers.