Style

The stigma, along with the style and ovary (often referred to as the stigma-style-ovary system), makes up the pistil, which is a portion of a plant’s gynoecium, or female reproductive organ. The stigma is made up of stigmatic papillae, which have pollen-receptive cells and form the distal section of the style or stylodia. These can be limited to the style’s apex or can cover a large area, especially in wind-pollinated species. 

Style

The style is a structure present within the flower in plants. The stigma and the ovary are connected by a long, slender stalk. The stigma is a sticky platform where pollen is placed near the apex of the style. The ovary is found at the bottom of the style and contains the ovules, which contain the egg cells and supportive cells required for reproduction. The pistil is made up of these three structures: the stigma, style, and ovary when they’re all put together. 

Structure of style

The stigmatic papillae are connected to the ovary by the style, which is a small upward extension of the ovary. It is sometimes absent, in which case the stigma is referred to be sessile. The majority of the styles are tube-like and come in both long and short lengths. The style can be open (with few or no cells in the central part) or closed (with a mucilage-filled central canal). It’s also possible to close the style (densely packed with cells throughout). Most syncarpous monocots and some eudicots have open styles, whereas many syncarpous eudicots and grasses have closed (solid) styles with specialised secretory transmission tissue that connects the stigma to the ovary’s centre. This creates a nutrient-rich environment for pollen tube development. 

When there are multiple carpels on a pistil, each one may have its stylodium or share a common style. The style of Irises and other members of the Iridaceae family separates into three petal-like (petaloid) style branches (also known as’stylodia’) close to the base of the style, forming a tribrachiate. These are tissue flaps that go from the perianth tube to the sepal. 

Attachment to the ovary

Terminal (apical), subapical, lateral, gynobasic, or subgynobasic are all possibilities. The most prevalent pattern is the terminal (apical) style position, which refers to the attachment at the ovary’s apex. The style rises to the side, somewhat below the apex, in the subapical pattern. Rosaceae have a lateral style that emerges from the side of the ovary. 

Pollination

To reach the ovules, pollen tubes expand the length of the style, and in some situations, self-incompatibility responses in the style prevent pollen tubes from fully developing. The pollen tube is directed to the micropyle of the ovule by the style in some species, including Gasteria. 

Functions of style

The pistil is a flowering plant’s female reproductive organ, and its three components work together to enable fertilisation and plant reproduction. Pollen, which includes male genetic material, settles on the stigma first and is held in place by the sticky surface. The pollen grain forms a pollen tube as it germinates on the stigma, which it will use to burrow through the full length of the style. The pollen tube emerges from the pollen grain and forms a tunnel connecting the stigma and ovary.

Two sperm cells are freed from the pollen grain and can move from the pollen grain down to the ovary when the pollen tube reaches the ovary. The sperm fertilises the egg that has been waiting in the ovule for a long time. The ovule grows into the plant’s seed or fruit after fertilisation, and if left uneaten, it produces another plant of the same species. 

The style is crucial during fertilisation since it is not only where the pollen tube originates, but it also plays a role in preventing incompatible pollen from accessing the ovary. Genetic information is transmitted between the pollen and the plant as the pollen tube begins to stretch within the style. The plant also produces poison during this period. The plant will release the poison to inhibit the formation of the pollen tube if the pollen is incompatible due to being from a different species or being too closely related, resulting in inbreeding.

Conclusion

The pistil stalk is referred to as the style. When pollen reaches the stigma, it begins to form a pollen tube, which will eventually reach the ovary, through the style. Because only appropriate pollen may form a pollen tube, the style acts as a buffer against pollen contamination.