Stamen: Parts, Types and Functions

Stamen is the male reproductive part of a flowering plant. The stamens are arranged in a whorl, collectively known as the androecium. They are found in the centre of the flower along with the stigma, if present. They can be either one in number or as many as thousands in number. The stamens can be arranged either spirally or in a whorl.

Parts of Stamen

A stamen is composed of a filament and an anther. The filament is a long stalk-like structure which supports the anther. The anther is a two-lobed structure which contains microsporangia for the production of pollen grains.

Small nectaries are found at the base of stamens which provide food for insect and bird pollinators.

Types of Stamen

Androecium falls into different categories depending on whether the filaments and anthers are fused or free. The categories are:

1. Polyandrous: In this type the filaments are not fused, they are free. E.g., Corchorus
2. Monadelphous: All the filaments in this type are fused together, but the anthers remain free. E.g., Hibiscus
3. Diadelphous: The filaments are fused in a group of two, while the anthers are free. E.g., Lathyrus
4. Polyadelphous: The filaments are fused in a group of more than two, and the anthers are free. E.g., Ricinus, Citrus
5. Syngenesious: in this type, all the anthers are fused together, and the filaments are free. E.g., Asteraceae
6. Synandrous: When all the anthers and filaments are fused together. E.g., members of Cucurbitaceae.

Stamens are divided into four other categories depending on the attachment of anther and filaments:

1. Basifixed: In this type, the filaments are attached to the base of anther lobes. E.g., Raphanus
2. Dorsifixed: The filament is attached at only one point on the dorsal side of the anther lobes. E.g., Passiflora
3. Adnate: The filaments run through the entire length of the anther, from base to top. E.g., Magnolia
4. Versatile: The filament is attached at the middle of the anther such that the anther swings free. E.g., Pancratium.

Functions of Stamens

• The anthers function as the site of pollen grain synthesis by the process of microsporogenesis.
• The filaments are known to nourish the anther with water and nutrients. It also aids anther in pollen dispersal by holding it in position.

Stamen Glossary

• Staminode: Some flowers produce sterile stamens, called staminodes. E.g., Cannonball tree, Penstemon sp.
• Antipetalous: The stamens are present opposite to the petals. E.g, Primrose
• Antisepalous: The stamens are present opposite to the sepals. E.g, Murraya
• Didymous: The stamens are of equal length present in two pairs. E.g, Galium
• Didynamous: The stamens are unequal in height in two pairs. E.g., Scrophulariaceae
• Tetradynamous: The stamens are arranged in a group of four with two long and two short filaments. E.g., Brassiceae
• Alternipetalous: The stamens are arranged alternately with the petals. E.g, Primulaceae

Explore BYJU’S Biology to learn more.

Also read:

• Flower – Parts And Functions
• Types of Pollination
• Cross Pollination vs Self Pollination