Endosperm
Endosperm
Endosperm (/ɛnˈdoʊˌspɜːrm/), from the Greek words endo (inside) and sperma (seed), is a tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes it an important resource for humans and animals, who consume it in the form of grains and seeds.
Etymology
The term "endosperm" originates from the Greek endo, meaning "inside", and sperma, meaning "seed". This reflects the endosperm's role as a nutritive tissue inside the seed that provides sustenance to the developing embryo.
Function
The primary function of the endosperm is to nourish the developing embryo. It achieves this by synthesizing and storing nutrients that can be used by the embryo during germination. The endosperm also plays a role in seed dispersal, as its nutritional content can attract animals who then disperse the seeds in their droppings.
Types of Endosperm
There are three types of endosperm development: nuclear, cellular, and helobial. The type of endosperm development affects the structure of the mature endosperm and can have implications for the seed's overall development and germination.
Nuclear Endosperm Development
In nuclear endosperm development, the endosperm nuclei divide without cytokinesis, resulting in a coenocytic endosperm. This type of endosperm is common in many species, including wheat and corn.
Cellular Endosperm Development
In cellular endosperm development, cytokinesis follows every nuclear division. This results in a cellular endosperm with cell walls. This type of endosperm is common in species like rice and beans.
Helobial Endosperm Development
In helobial endosperm development, the endosperm initially develops by cell division at the micropylar end of the embryo sac, forming two distinct domains. This type of endosperm is common in species like orchids.
Related Terms
- Embryo: The part of a seed or plant that develops into a new plant.
- Seed: A mature fertilized plant ovule, consisting of an embryo and its food source.
- Germination: The process by which a plant grows from a seed.
- Cytokinesis: The division of the cytoplasm to form two separate daughter cells after mitosis.
External links
- Medical encyclopedia article on Endosperm
- Wikipedia's article - Endosperm
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