Angiosperms – Flowers

Flowers are an exclusive structure of angiosperms , they are the reproductive organs of these plants.

They can be lonely or in groups called inflorescences .

The main function of flowers is to produce seeds so that new plants are formed when they germinate.

Usually the flowers are colorful and have odors to attract their pollinators .

Index [ hide ]

  • Flower structure
  • Classification of flowers
  • Ginceu and androceu
  • Pollination of flowers

Flower structure

The parts of a flower are called whorls. These  are modified leaves, usually arranged in circles.

The flowers have four floral whorls: chalice, corolla, androceu and gynecium, and two support structures: peduncle and receptacle.

Peduncle

It is a stem that holds the flower to the stem and supports its weight.

Receptacle

It is the end of the peduncle, it is dilated to receive the other whorls.

Cup

Most of the time, it presents green color. It is the most external whorl and serves as a protective barrier for the flower. It is popularly known for sepals.

Corolla

Popularly known as petals, this is a whorl that attracts attention in most flowers because they can have color, aroma and also produce sweet secretion to attract pollinators.

Androceu

Male flower organ, composed of a set of stamens that has a stem called a fillet, connected to an enlarged end called anther.

Gynecium

Female flower organ, formed by modified leaves called carpels or pistils. It has an enlarged base called an ovary, a stem called a fillet and an opening known as a stigma.

Classification of flowers

The flowers can be classified as they contain all the floral whorls and be a complete flower, or it can have any of the whorls  missing , being called in this case an incomplete flower.

Flowers – Structure of complete and incomplete flowers.

Flowers are also used to classify the sex of plants :

  • Monoic : incomplete flowers, the same individual produces two types of flowers, one with androceu and the other with gynecium;
  • Dioicas : incomplete flowers, one with androceu and the other with gynecium, but produced by different individuals;
  • Hermaphrodites : complete flowers, with gynoecium and androceu in the same flower;
  • Polygamous : it has complete and incomplete flowers in the same individual.

Ginceu and androceu

Gynecium

The gynecium is a set of modified leaves  that form the female reproductive organ of the flower, these leaves are  called carpels or pistils.

Carpels have several regions, the most prominent being ovary where female gametes are  .

The  rod-shaped region that connects the ovary to the stigma is the stylus and the stigma is the opening that receives the pollen grain.

The ovary will develop after the fertilization of the gametes and will form the fruit .

Androceu

It is the male part of a flower, formed by a set of stamens.

The stamens have a long stem called a fillet and a pollen grain producing structure called anther.

Pollination of flowers

It is through pollination that fertilization of gametes occurs.

For one gamete to find the other, most of the time it is necessary to use biotic and abiotic factors.

Pollination can happen on the same flower that produced the two gametes, thus being self-pollinated.

It can also happen between different flowers from the same individual or from different individuals, what we call cross-pollination.

Flowers – Pollination

You must have already seen the variety of morphologies that the flowers present, this is because there are several types of pollination and each one needs the plant to adapt for it to occur.

We can mention among the types of pollination: anemophilia (by wind), hydrophilia (by water), artificial (through human intervention), entomophilia (by insects) and ornithophilia (by birds).

 

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