Flowers (also written as Hana and Hana. Flowers-oysters often written as "flowers" due to restrictions on kanji) are plants that grow and attach, and many are decorated with beautiful petals. When the flowers die, they produce fruits and seeds. Many are used for ornamental purposes. Biologically, it is the reproductive organ of seed plants. Also, as a representative organ of plants, it is often used as a synonym for "plant (seed)" itself. Plant flowers are called fresh flowers, and flowers made of paper, cloth, metal, etc. are called artificial flowers.
Definition of flowers
Flowers are the reproductive organs of seed plants, including pistils and stamens (some of which are absent), and composed of spore leaves (flower leaves) and sterile appendages on a single finite stem apex.
However, there are multiple ways of thinking about its strict definition.
The idea of using the reproductive organs of angiosperms as flowers
The idea of using a reproductive organ with an ovule as a flower (angiosperms and gymnosperms)
The idea that flowers are densely packed with reproductive organs Flowers are thought to have arisen from a structure in which spore leaves are solidified at the tips of branches. It can be said that the original structure such as, and even the spore leaves of Sugina, such as Tsukushi, are flowers. It can be said that 2 is a flower up to the pine cone, and 3 is a position that Tsukushi is also a flower.
1 is mostly for American researchers and 2 is for European researchers. In the 19th century, the idea of 3 was the mainstream, but now the most rational 2 is becoming the mainstream.
The structure of the whole flower can be regarded as a very short and clogged structure in which large sporophylls, microspore leaves, and fruitless leaves are lined up from the tip on one branch.
A typical flower has a pistil in the center, with a pistil at the tip of a handle extending from a branch, and a stamen surrounds it. Petals and calyxes are placed around it. Pollen is produced in the stamens, and ovules are contained in the pistils. Seeds are produced by the action of both.
In gymnosperms, male and female flowers are common, and the scaly structures derived from sporophylls are usually arranged around the axis.
Angiosperms often have many decorative structures such as petals and calyxes. Therefore, the structure is such that the pistil derived from the large sporophyll in the center, the stamen derived from the microspore leaf on the outside, the petals derived from the leaf on the outside, and the calyx derived from the leaf on the outermost side. The petals and calyxes are collectively called the perianth. However, not all flowers have such a structure, and many flowers do not have petals or calyxes. In particular, many anemophiles have petal defects or degeneration. In the case of Gramineae, such flowers are called spikelets.
Many flowers have stamens and pistils in one flower, but some have only one of them. Even if both stamens and pistils are provided, there are many cases where one is not functioning or one of them ripens first and does not ripen at the same time.
The arrangement of flowers is called inflorescence. The inflorescences vary from flower to flower, but they are arranged according to a certain method.
Bracts are the leaves that attach to the base of flowers and inflorescences. Also called bract. Some are usually small but petal-shaped.
It is considered that as the seed plant evolved from the fern plant, the sporophylls that attach the microspores to the male buds and the sporophylls that attach the large spores to the female buds changed. Also, the petals and calyxes are considered to be of leaf origin.