STAMEN: PARTS, FUNCTIONS AND TYPES - BIOLOGY - 2025

The stamen is the male reproductive structure of flowering plants. It is generally composed of a long, thin filament and a bilobar anther at the apex. All the stamens of a flower, collectively, are called androecium or androecium.

The stamens can be found in the flowers in a very varied number, from just one to many. They can also all be linked together, forming groups, or completely separate.

Close-up of the stamen and stigma, of the flower Lily 'Stargazer (Lilium sp.) Taken and edited from Subhrajyoti07.

They have taxonomic importance, which means that they can be used to separate groups of plants; For example, the flowers of the Cactaceae (cactus) family are characterized by having many stamens, whereas those of the Orchidaceae (orchids) family generally have only one stamen.

Parts

The stamens are made up of two structures that are the filament and the anther. Its relevant characteristics are described below:

Filament

Also called the sterile part of the stamen, the filament is the basal part of the stamen, it is located below the anther and is the structure that supports it. In most cases it is thin and cylindrical in shape.

Although they are generally thin and cylindrical, the filaments can become laminar, wide and thick, and of lengths ranging from very long to short and can even be absent.

Anther

This part is known as the fertile structure of the stamen. It is attached to the filament, but the place of attachment on the anther and the way it is attached can vary.

The anthers can be attached to the filament at its base (basifix), on the back (dorsifix), along its entire longitudinal axis (adnatas), or at one point and can freely oscillate on the filament (versatile).

Generally, an anther is made up of two teak, although some anthers of a single teak have also been found. When it has two theca, they are joined by connective tissue. In each teak there are a pair of pollen sacs, corresponding to a microsporangium (structure where spores are formed).

Commonly there are a pair of pollen sacks for each teak for a total of four pollen sacks, but there may be exceptions where the number of sacks may be greater or even less.

Features

The function of the stamens is reproductive. It is the male structure of the plant where pollen develops and prepares for pollination.

There is another type of stamens called stamiodia that do not participate in the reproductive process of plants; they are called atrophied or sterile stamens. They are often observed in the inner whorl of the flower.

In some plants of the Hamamelidaceae family, the stamiodial stamens are modified for the production of nectar.

Types

Science has managed to differentiate various types of floral stamens and has separated them in multiple ways: according to the number, length, proportion, place of insertion and even the connection of the stamens, depending on whether they are fused in the same spiral or in more of one.

Depending on the case, this classification or separation is of systematic importance, since flowering plants have a certain specificity with stamens.

Merged into the same spiral (connate)

Monadelfo

Stamens whose filaments are linked together by their filaments forming a kind of bundle. This type of stamen can be observed, for example, in plants of the Myrtaceae family, a taxonomic group to which the eucalyptus (Eucalyptus) belongs.

Diadelfo

Word derived from the Greek dis, means two and adelphos, which means brother. It is used to define the stamens that are joined together by the filaments, forming two different bundles.

This type of stamen is characteristic of plants of the Fabaceae family. An example of this family is the legume from which the chickpea (Cicer arietinum) is used.

Polyadelfo

Stamens that are joined together by the filament are known as polyadelphs, forming three or more different bundles. It is characteristic of a large number of plants, such as those of the Rutaceae family, where the Citrus genus is located, to which plants such as lemon, mandarin, bitter orange, among others, belong.

Polyadelph stamens scheme. Taken and edited from: Pérez Morales (1999), svg: User: RoRo.

Sinantéreos

Sinantéreos stamens are those whose anthers are concrete or are attached to a single body. In this case only the anthers are connate. These are typical (but not strict) of the Asteraceae family, of which sunflowers (Helianthus annuus) and chamomile (Matricaria spp.) Belong.

Merged in more than one spiral (DNA)

Epipetal

In flowers whose petals are fused, also called sympathetic, the filaments are united at the base of the corolla and not in the receptacle as they generally are; this is called the epipetal stamen.

Characteristic for example of the Primulaceae family, to which many garden plants belong, such as the famous imperial violet (Cyclamen persicum).

Didynamo

The stamens that emerge from the flower in two pairs are known as didynamos, of which two will be longer than the other pair. This type of stamens has been observed, for example, in plants of the Bignoniaceae family to which the plant called pumpkin tree belongs, also called taparo (Venezuela) or totuma tree (Colombia and Panama).

Tetradynamic

Tetradinamic stamens are recognized by presenting six stamens, of which two are shorter than the rest (four stamens).

An example of plants with tetradyne stamens are those of the Brassicaceae family; In this there is a species with high scientific interest such as Arabidopsis thaliana, used for molecular studies of genetic mapping.

Other types

According to the length of the stamens

When the stamens are short and do not extend beyond the corolla, they are called inserts or included, while if their length is such that they extend beyond the corolla, then they are called exerts.

According to the position of the anthers

As already mentioned before (see Parts, anther), various types of stamens are known according to the position of the anther with respect to the filament and these are adnate, basifix, dorsifix and versatile.

According to the dehiscence

The dehiscence in the anthers is the moment in which they open to release the pollen and depending on the way they do it they are separated into several types. For example, when the anthers open longitudinally, an opening in each teak is known as a longitudinal type. Other types are transverse, poricidal, and valvar.

Another example of dehiscence in the stamens is referred to the direction of the teak in relation to the center of the flower. In some plants the teak is inserted facing the center of the flower; in these cases the dehiscence occurs inside the flower (intrusive dehiscence), facilitating self-fertilization or rather self-pollination.

Stamens of the flower Picris echioides. Known for self-pollinating as a secondary breeding method, in the event that cross-fertilization has not been successful. Taken and edited from: Hildesvini.

When the teak is inserted into the dorsal face of the filament, then it looks towards the outside of the flower; in that case the dehiscence is said to be extruded.

References

1. RJ Scott, M. Spielman, HG Dickinson (2004). Stamen Structure and Function. Flower development.
2. Stamen. Encyclopædia Britannica. Recovered from britannica.com.
3. M. Hickey, C. King (1997). Common Families of Flowering Plants. Cambridge University Press.
4. Stamen. Wikipedia. Recovered from en.wikipedia.org.
5. Stamens. EcuRed. Recovered from ecured.cu.
6. Morphology of vascular plants. Theme 4: Flower. National University of the Northeast. Recovered from biologia.edu.ar.
7. Morphology of the stamens. EcuRed. Recovered from ecured.cu.
8. Anther. Wikipedia. Recovered from es.wikipedia.org.