Androecium

Androecium :-

Androecium is the male reproductive organ in a flower. It is found in the stamen of the flower and is made up of two parts: anther, which is a yellowish sac-like structure responsible for pollen production and filament which has a very thin structure that sustains the anther. Plants have their reproductive structures in the flowers. The number of petals, sepals, stamens, and pistils can vary amongst plants and can comprise all-female parts, all-male parts or both. Let’s have a closer look at androecium and discuss some important questions

What is Androecium ?

                                                  Androecium

There are four whorls in a typical flower. Calyx, corolla, androecium, and gynoecium are the four parts of the flower. The androecium is the third whorl in a flower and emerges from the corolla's inner side. The androecium is the flower's male reproductive component and is made up of stamens. An anther and filament are also parts of a stamen. The anthers seen inside the bloom are usually bilobed. Two microsporangia are seen in each lobe of the anther which are also known as pollen sacs that form pollen grains.

Components of Androecium

An anther and filament make up a stamen. The anther is a bilobed structure at the end of the flower. A long and slender stalk makes up the filament. The filament's proximal end is still linked to the flower's thalamus or petal. The two anther lobes are separated by a large groove towards the front. The two anther lobes are joined together by a connective band of tissues. An anther has a tetragonal structure with four sides. Four microsporangia are situated at the four corners of this structure and each lobe has two of them. A mature anther is thus tetrasporangiate. Microsporangia produce pollen sacs, which are loaded with pollen grains when they reach maturity. The outline of a microsporangium is approximately round and contains primary sporogenous cells. They consist of a homogeneous mass of meristematic cells enclosed by the anther wall. The microspore mother cells are formed by them.

Anther Wall Layer

There are four walls in an anther. They are as follows:

• Epidermis: The epidermis is the anther's outermost layer. It is a single layer that functions as a protective barrier. Exothecium is a fibrous thickening that occurs in some plant species, such as Arceuthobium.
• Endothecium: Alpha-cellulose fibrous bands can be found in the cells of the endothecium layer. These bands emerge from the anther's inner tangential walls and aid in its dehiscence. This is due to their hygroscopic properties. These bands are not present in hydrophytes.
• Middle Layer: These are transitory cells. They have 1-3 layers and deteriorate as they grow older.
• Tapetum: The innermost layer of the anther wall is called the tapetum. The sporogenous tissue is surrounded by this layer. These cells provide sustenance to the pollen grains. These cells have several nuclei and a lot of cytoplasms. These cells are polyploid because they have more than one nucleus. In addition, the DNA content of these cells has increased. Endomitosis, Restitution nucleus, and Polyteny all contribute to the increase in DNA content.
  
  
  

Pollen Grain

The male gametophyte, or androecium are called pollen grains. Pollen grains are spherical structures with a diameter of 25-50 micrometers. Their cell wall is referred to as sporoderm and is made up of two layers called exine and intine.

Types of Androecium

 

Monandrous, Diandrous, Triandrous, Tetrandrous, Polyandrous, Monadelphous, Diadelphous, Polyadelphous, Syngenesious, Synandrous, Antipetalous, Antiphyllous, Alternipetalous, Epipetalous, Episepalous, Epiphyllous and a few others are some of the types of androecium. Some of them are defined below-

• Monandrous- Flowers with only one stamen are called monandrous. Euphorbia, for example, has only one stamen.
• Diandrous- Flowers with two stamens are called Diandrous. Coronopus, for example, has two stamens.
• Triandrous- Flowers with three stamens are called Triandrous. Triticum, for example, has three stamens in its flowers.
• Tetrandrous- Flowers with four stamens are called Tetrandrous. Scoparia, for example, has four stamens.
• Polyandrous- Flowers with five or more free stamens are called Polyandrous. Corchorus, for example, has a lot of stamens and they're all free.
• Monadelphous- When all of the filaments are fused to create a single tube, yet the anthers remain free, as in Hibiscus.
• Diadelphous- When filaments are grouped with their anthers free, as in Lathyrus.
• Polyadelphous- When filaments are grouped yet their anthers remain free, as in Ricinus, Citrus, and other plants.
• Syngenesious- When all anthers are grouped with their filaments free, as in the Asteraceae family.
• Synandrous- When all anthers and filaments come together to form a single group, such as in Cucurbitaceae members.
• Antipetalous- Flowers with stamen on the opposite side of the petals. Coriandrum, for example, has stamens on the opposite side of the petals.
• Antiphyllous- Flowers that have stamens on the opposite side of the tepals. Chenopodium, for example, has stamens on the opposite side of the tepals.
• Alternipetalous- When stamens are arranged in a pattern that alternates with the petals.
• Epipetalous- When stamens are linked to the petals of a flower, such as a Petunia.
• Episepalous- When stamens and sepals are fused, as in some Verbena species with no petals.
• Epiphyllous- When a flower’s stamens are united with tepals. Asparagus, for example, has stamens united with tepals.

Things to Remember

• There are four whorls in a typical flower. Calyx, corolla, androecium, and gynoecium are the four parts of the flower. The androecium is the third whorl in flower.
• The androecium is the flower's male reproductive component. It is made up of stamens. An anther and filament are also parts of a stamen.
• The anther is a bilobed structure at the end of the flower. A long and slender stalk makes up the filament. The filament's proximal end is still linked to the flower's thalamus or petal.
• There are four walls in an anther. They are as follows: epidermis, endothecium, middle layer, and tapetum.
• The male gametophyte, or androecium, is represented by pollen grains. Pollen grains are spherical structures with a diameter of 25-50 micrometers. Their cell wall is referred to as sporoderm. Exine and intine are the two layers that make up this sporoderm
• Monandrous, Diandrous, Triandrous, Tetrandrous, Polyandrous, Monadelphous, Diadelphous, Polyadelphous, Syngenesious, Synandrous, Antipetalous, Antiphyllous, Alternipetalous, Epipetalous, Episepalous, Epiphyllous and a few others are some of the types of androecium.