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Thursday 20 November 2008

FAMILY OF THE WEEK : PAPAVERACEAE


Argemone mexicana




California poppy (USA)

California poppy (USA)

FAMILY OF THE WEEK : PAPAVERACEAE

In India this family has 5 genera and about 20 species mostly confined to the Himalayas.

Vegetative characters:

Mostly perennial herbs with a milky or coloured latex.

The leaves are radical or alternate, exstipulate, simple and entire or more often lobed or divided.

Inflorescence and flowers:

The flowers are solitary at the end of main or lateral branches. Sometimes racemes or panicles. The flower buds are often nodding due to more rapid growth of one side of flower stalk.

The flowers are large showy, complete, hermaphrodite, actinomorphic, di-or tri merous and hypogynous.

The sepals are two or three(Argemone), free or united, imbricate and caduceus.

The petals are four to six, biseriate, imbricate and often rolled or crumpled in bud.

The androecium consists of numerous free stamens in several whorls; the filaments are slender; and the anthers are erect, dithecous, extrorse and opening lengthwise.

The gynoecium is of two to many carpels, and it is syncarpousThe ovary is superior and unilocular. The style is very short or absent and the stigmas are as many as carpels, radiating connate and opposite or alternating the placenta.

Fruits and seeds:

The fruit is a many seeded capsule opening by pores or by valves under the lobes of persistent stigmas. The seeds are small with a minute embryo and a copious fleshy fleshy or oily endosperm.

Pollination and seed dispersal:

Self and cross pollination.Flowers do not contain nectar and are visited by pollen seeking insects. The seeds are usually dispersed by wind or by birds, animals or human beings. The seeds of Papaver and Argemone are dispersed by adhesion to animals, carts or feet of humans.

Examples:

Papaver somniferum L: Opium poppy

Papaver rhoeas (Corn poppy)

Papaver nudicaule (Iceland poppy)

Papaver orientale (Oriental poppy)

Argemone mexicana

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