Angiosperms: Definition, Characteristics, Syngamy, and Triple Fusion
Angiosperm: Definition
The term Angiosperm is derived from the Greek word Angelion means bottle or vessel and Sperma means seed by Paul Hermann 1960. Angiosperms are also called flowering plants because of the presence of a Flower. The Angiosperms are also known as Fruiting plants as they produce seeds and fruits. The Angiosperms is the most diverse group that includes 64 orders, 416 families, and 3,000,000 species. Seed plants with sporophylls grouped into flowers and seeds generated inside fruits are known as angiosperms. They are the most evolved plants on the planet and make up the majority of the current vegetation. It includes trees, shrubs, vines, and herbs adapted to almost every environment.
Characteristics of Angiosperms
1. Angiosperms or flowering plants occur in most environments on the Earth.
2. Angiosperms are covered seed-bearing plants.
3. the Herbs, shrubs, trees, twiners, trailers, and climbers, among others, make up the sporophytic plant body.
4. The Gametophytic phase is highly reduced and only represented by a few cells. The free-living existence of Gametophyte is absent.
5. Vascular tissue is well developed, Xylem and Phloem are present. The xylem contains tube-like structures that are vessels, tracheids, xylem parenchyma, and xylem fibers. Phloem contains a tube that is a sieve tube, companion cells, phloem parenchyma, and phloem fibers.
6. Sporophylls are aggregated to form flowers. In the case of Gymnosperms, sporophylls are woody and in Angiosperms sporophylls are delicate.
7. Flowers contain male and female reproductive parts. Stamen contains Anther and inside Anthers, there are four microsporangia. After meiosis, it results in the formation of haploid microspore and haploid pollen grain. The pollen grain forms male gametophytes. The female part is represented by Carpel or Pistil.
8. It shows Double fertilization.
9. It shows triple fusion i.e. formation of Endosperm i.e. one male gamete fuses with egg forms a zygote and the other fuses with a secondary nucleus for the formation of Endosperm.
10. They show secondary growth due to the development of cambium.
11. Production of two kinds of spores i.e. microspores (pollen grains) and megaspores. Thus Angiosperms are heterosporous.
12. Pollination occurs through several agencies viz. wind, water, animals, etc.
13. Archegonia is absent and female gametophyte is represented by embryo sac.
Differentiate between Syngamy and Triple Fusion
| Characters | Syngamy | Triple Fusion |
| Definition | It is the fusion of the male gamete with the female gamete to form a zygote | In angiosperms, it is the process of the male gamete fusing with the diploid secondary nucleus. |
| Result | Forms Zygote | Forms triploid Endosperm |
| Function | Zygote forms Embryo | The endosperm provides nourishment to the developing embryo |