Conceptual diagram of stamen structure:

stamen is the female reproductive organ of seed plants. Located in the central part of the flower, it is one of the components of the flower and is owned by higher plants. According to different structures, they can be divided into stamens and pistils. The part between the stigma and the ovary of the pistil, connecting the stigma and the ovary, is the passage for the pollen tubes to enter the ovary. Its length varies depending on the plant species. The style of corn can be up to 40 cm long, while the style of rice, wheat and other crops is extremely inconspicuous. When the pollen tube grows along the style and extends towards the ovary, the style can provide it with nutrients and certain chemotactic substances.

Ovary

The enlarged part at the base of the pistil has one or more chambers, each chamber containing one or more ovules. After pollination and fertilization, the ovary develops into fruits and the ovules develop into seeds. There are several different types of positional relationships between the ovary and the flower due to the different shapes of the receptacle and whether it is connected to the ovary wall.

(1) The ovary is superior. There are two situations: one is that the receptacle is domed or flat-topped, and the bottom of the ovary is attached to the receptacle and is located higher than other parts of the flower. The calyx, corolla and stamens are grouped on the receptacle below the pistil, and are called superior and inferior ovary flowers. Such as peonies and broad beans. The other type is that the receptacle is sunken into a cup or pot shape. Although the ovary is still attached to the receptacle at its base, all parts of the flower are located around the ovary, which is called superior ovary or peripheral flower. Such as peach and rose;

(2) The ovary is semi-inferior. The lower part of the ovary is healed with the receptacle, and the calyx, corolla, and stamens are clustered on the higher position of the receptacle around the ovary, which is called a semi-inferior ovary, or a peripheral flower. Such as Taiping pistil;

(3) The ovary is inferior. The torus and ovary wall are completely or almost completely healed, and the ovary is in the lowest position. The calyx, corolla or stamens cluster on the edge of the upper receptacle of the ovary, which is called the lower ovary and the upper flower. Such as melons.

Stigma

The part at the top of the pistil that receives pollen. Usually enlarged into a globular, disc-shaped or branched pinnate shape. Often have papillae or short hairs to facilitate the reception of pollen. Some stigmas secrete mucus (moist stigma) on their surface, which is suitable for pollen fixation and germination. Some stigmas do not produce secretions on their surface (dry stigmas), but the hydrophilic protein film covering the surface also plays a role in adhering to pollen and helping pollen obtain the moisture necessary for germination.

Stames

Morphological structure

The pollen-producing organ of seed plants. It consists of two parts: filament and anther. Located inside or above the perianth, arranged in a whorl or spiral on the receptacle. The number varies depending on the plant species. Usually, the number of primitive species is large but not necessarily certain, and the number of higher species tends to decrease and reach a certain number. All the stamens in a flower are collectively called the stamen group.

Filament

The stalk-like part at the base of the stamen plays a role in supporting and stretching the anthers. They are generally as long and thin as silk, but they can also be as flat as a belt (such as a lotus), or disappear completely (such as a gardenia), or transform into a petal shape (such as a canna). The length of the filaments, free or conjoined, varies depending on the plant species. Filaments within the same flower are usually of equal length. But there are also filaments of different lengths in the same flower. For example, in the flowers of Brassicaceae plants, there are 6 stamens divided into two whorls, the outer whorls of two stamens have shorter filaments, and the inner whorls of four stamens are longer, which are called four strong stamens; in the flowers of Lamiaceae and Scrophulariaceae plants, , the filaments of the four stamens are two long and two short, which are called two strong stamens. The filaments are usually separated from each other, but some are also partially or completely joined together. For example, the filaments of cotton are combined into one bundle, which is tubular, and are called monomeric stamens; the filaments of broad beans and black locust are combined into two bundles, called dimeric stamens; castor The filaments are connected into multiple bundles, which are called multi-body stamens.

Anthers

The sac-like part at the top of the filament. The medicine compartment is often divided into two medicine chambers, each medicine chamber has 1 or 2 pollen sacs. The pollen sac is where pollen is produced. The wall of the anther is composed of epidermis, fiber layer, middle layer and tapetum. The tapetum is a special cell layer around pollen sacs, with a dual-nucleated or multi-nucleated structure. The cells contain more RNA and proteins, as well as nutrients such as oils and carotenoids, which provide the necessary conditions for the development of pollen grains. Need nutrients. When the pollen matures, the pollen sacs split open on their own, releasing the pollen. According to the way the anthers are attached to the filaments, they can be divided into full-type anthers (all the anthers are attached to the filaments, such as lotus) and bottom-type anthers (the anthers are attached to the top of the filaments with their bases, such as sedges and flatgrasses). etc.), carried medicine (the anther sticks to the filament with its back, such as verbena, dogwood, etc.), T-shaped medicine (the anther lies horizontally, and is attached to the top of the filament with a point in the center of its back, such as lily, rice, etc. ) and several other types. The stamens and filaments of Asteraceae plants are separated and the anthers are united, which is called polystamen.