Stamen - Structure, Functions and Types - Biology Class 12

CBSE Class 12 - Sexual Reproduction In Flowering Plants - Stamen: Stamen is the plant reproductive organ. Stamen produce pollen and usually consists of anthers and filaments. The stamen is a key component of the flower, which is the reproductive structure of angiosperms. The stamen's function is to produce and release pollen, which is then transported to the female reproductive structure of the plant, the pistil, to facilitate fertilization and seed formation. The stamen's structure and arrangement vary depending on the species of plant, and can be a useful characteristic for plant identification.

What is Stamen?

In flower stamen is the male reproductive component. The stamens are organized in a whorl, which is referred to as the androecium. These are found in the flower's center, along with the stigma, if present. They can be as few as one or as numerous as thousands. The stamens might be spiraled or placed in a whorl.

Stamen is the male reproductive organ in flowering plants. It produces and releases pollen, which contains the male gametes (sperm cells) that fertilize the female gametes (egg cells) in the pistil.

Characteristics of Stamen

The stamen is a modified leaf-like structure made up of two major parts: the filament and the anther. The filament is a thin stalk-like structure that supports the anther, which is a sac-like structure containing pollen.

There are several types of stamen that can be distinguished based on their physical characteristics, including:

• Perfect stamens: These stamens have both a filament and an anther and are capable of producing viable pollen.
• Imperfect stamens: These stamens won't consists of filament or anther and can't produce viable pollen
• Stamens with appendages: Some stamens may have additional structures attached to the filament or anther, such as hairs, scales, or wings.
• Stamens with specialized functions: In some plant species, stamens may have specialized functions beyond pollen production, such as attracting pollinators or providing structural support.
• Fertile and sterile stamens: In some flowers, the stamens may include both fertile (capable of producing pollen) and sterile (non-pollen-producing) structures.

Structure of Stamen

• Filament: The filament is a long, slender structure that holds the anther in place. It is typically a slender, elongated structure linked to the flower's base. The filament is composed of elongated cells that support the anther.
• Anther: An anther is a sac-like structure near the top of the filament. It has four pollen sacs that generate and release pollen grains. The male gametes are contained in the pollen grains, which are microscopic, oval-shaped entities.

Functions of Stamens

• The anthers serve as the location of pollen grain synthesis via the microsporogenesis process.
• The filaments are known to provide hydration and nutrients to the anther. It also helps pollen dispersal by holding the anther in place.

Types of Stamen

• Diadelphous: Here, anthers are free, but the filaments are fused in groups of two. Example: Pea.
• Syngenesious: Here, filaments are free, and anthers are fused. Example: Marigold and Sunflower.
• Synandrous: In this condition, all the anthers and filaments are fused together. Example: Cucurbita.
• Polyadelphous: Here, anthers are still free, but the filaments are grouped together in more than two groups—for example, Citrus plants.
• Polyandrous: In this kind, the filaments are not combined; they are free—for example, Lotus and Rose.
• Monadelphous: In this condition, anthers are free, and filaments are fused. Example: China Rose.