Tokhirjonova Mushtariy Ibratbek
By: Tokhirjonova Mushtariy Ibratbek
Annotation:
This thesis provides a detailed explanation of the structure and types of seed buds, their importance in seed formation, the internal structure of seed buds, and the types of orthotropous (straight), anatropous (inverted), and campylotropous (oblique) seed buds.
Abstract:
This thesis discusses the types of seed bud structure, their importance in seed formation, the internal structure of the seed bud, and the types of straight, inverted, and oblique seed buds.
Keywords: Seed bud, placenta, androecium, gynoecium, micropylar, chalazal, nodule, orthotropous, anatropous.
Seed bud (ovulum) – is a protuberance usually found inside the ovary of the carpel in the flower of higher plants, formed after fertilization. The seed bud is located on a special protrusion on the placenta, which is part of the fruit leaf, and can be single or multiple; it is usually spherical or ovoid in shape. The central part of the seed bud consists of the nucellus, which is covered by one or more layers of integuments. These integuments may grow to form a single common coat.
The seed bud consists of micropylar and chalazal regions. In the micropylar part, the integuments do not fuse entirely, forming a pollen tube pathway or micropyle. After fertilization of the egg cell, the seed develops from the seed bud.
In the course of evolutionary development, seed buds first appeared in seed ferns. Among angiosperms, the seed bud is highly developed and protected within the ovary from external unfavorable conditions. After fertilization, the integuments turn into the seed coat. A single ovary can form from one to several thousand seed buds. Depending on their orientation to the placenta, seed buds are classified as orthotropous (straight), anatropous (inverted), or campylotropous (oblique), with transitional forms also existing. Seed buds can be located in various positions inside the ovary: in the central part, on the ovary wall, or at the base.
Seed buds are located in the central column of the gynoecium. This type of gynoecium is found in families such as Caryophyllaceae and Malvaceae. The ovary connects to the floral axis. When the ovary is superior, it is formed from free carpels. If the ovary wall fuses with other floral parts at the base but not at the top, the ovary is considered half-inferior.
Structure and types of seed buds:
Depending on the plant species, one to several thousand seed buds may be present inside the ovary. The seed bud is a modified megasporangium and consists of a central part – the nucellus – surrounded by one or two integuments and a stalk called the funiculus. The nucellus is composed of parenchymatous cells and develops differently in different plants.
According to the development of the nucellus, seed buds are divided into two groups:
- Crassinucellate seed buds – have a well-developed nucellus. Found mostly in monocotyledons and primitive dicots.
- Tenuinucellate seed buds – have a poorly developed nucellus. Common in advanced dicotyledons.
The nucellus is externally covered by one or two integuments. In some plants, these coverings are reduced, and the seed bud becomes naked. In very rare cases, seed buds may have three integuments. The third layer forms as a result of the separation of the outer integument. At the top of the seed bud, the integuments do not completely fuse and remain partially open.
Andijan State Pedagogical Institute
Faculty of Natural Sciences, Biology Department
Student of Group 103 – Tokhirjonova Mushtariy Ibratbek
Similar Posts by The Mt Kenya Times:
- Mt Kenya Times ePAPER August 26, 2026
- Mt Kenya Times ePAPER August 25, 2026
- Mt Kenya Times ePAPER August 24, 2026
- Diaspora Times Global Aug 22 – Aug 28, 2026
- Mt Kenya Times ePAPER August 21, 2026
About the Author
