pistil

Article

May 21, 2022

A pistil (pistil, pistil, English: Pistil) is a female reproductive organ that is present in one or more flowers of angiosperms (amphoteric or female flowers) and is commonly referred to as a "pistil". It has the function of protecting the embryo sac, which is a female gametophyte, inside, accepting pollen, which is a male gametophyte, and playing a role in pollination between the gametes formed by both. In addition, after the seeds have grown inside, they become the prototype of the fruits formed around them. There is one or more in the flower (if there are more than one, the whole is collectively called Gynoecium). The unit that constitutes the pistil and is homologous to the leaves is called the carpel (Shinpi, English: Carpel), and one pistil is one (separate carpel) or multiple carpels (combined carpel: this). In the case, the flower has only one pistil). The carpel corresponds to the large sporophylls of ferns and gymnosperms.

Form

The pistil is divided from the base to the tip as follows: The ovary (ovary) is the puffy part under the style and contains the ovule (which becomes the seed after fertilization). After fertilization, it grows and becomes a fruit. The style is an elongated part that connects the stigma and the ovule, and has a passage that extends the pollen tube to the ovule. The stigma (stigma) is located at the tip, has no epidermis, and is a specialized organ for receiving pollen. Usually sticky. Some species (Papaveraceae, etc.) have no style and have a stigma directly on the ovary.

Position

The pistil constitutes the innermost part of most flowers. In many flowers, the other parts (calyx, petals, stamens) are attached to the corolla below the pistil. In this case, the ovary is above the other parts and is said to be above the ovary. In cherry blossoms, peaches, roses, etc., the other parts are fused to form a tubular calyx. In this case, the ovary is located below the calyx, petals and stamens in position, but is thought to be above the stamens, and such flowers are called the ovary circumference. A flower in which the calyx tube fuses with the ovary and the calyx, petals and stamens appear to emerge from above the ovary is called the lower ovary. Examples include apples, pears, cucurbitaceae, and asteraceae, many of which have fruit-like roots in the calyx. In addition, the flowers in which the ovary is half buried in the calyx are called the middle ovary, and there are primroses and the like. Fruit formation also differs depending on the position of the ovary, which is important for plant identification and classification.

Phylogeny

The carpel differentiates into a ovary at the root, a style at the tip, and a stigma. The carpel is phylogenetically homologous to macrospore leaves and is thought to be derived from a leaf-like structure (the image of a cycad pistil, shaped like a collection of leaves). There are various theories about the process, but in summary, the carpel is folded or fused (combined) to form a cavity (ovule) inside, and the part where the ovule is attached (placenta) is inside. It means that it was possible. In fern plants, spores released from the sporophyte germinate on the ground to form anterior lobes, where eggs and sperms are formed, and the sporophytes (fern plants) are newly formed by the fern. It is probable that the flow of doing things has reached the current state through the following steps. First, there was a difference between macrospores and microspores, with female anterior lobes (forming only eggs) from the former and male anterior lobes (forming only sperms) from the latter. Large spores now germinate on the sporophyll and in the spore sac