Angiosperms

Introduction

Angiosperms refer to those plants that produce seeds and bear fruits. Angiosperms belong to the Plantae and spermatocytes. However, both gymnosperms and Angiosperms are seed-producing plants, but gymnosperms bear flowers, and there is endosperm within their seed. Unlike gymnosperms like conifers and cycads, angiosperm seeds are found in flowers. Also, gymnosperms produce fruits that contain seeds. Angiosperms come in a wide range of shapes and sizes. Herbs, shrubs, trees, vines and succulents are among them. They can be found in a wide range of habitats, including woods, grasslands, deserts, and aquatic and marine areas.

Characteristics Of Angiosperms

Let us look at some of the characteristics of angiosperms:

• Angiosperms are flower-bearing plants. It is the most distinguishable feature that distinguishes angiosperms from other seed-bearing plants
• Angiosperms have much smaller and lighter pollen grains than gymnosperms
• Unlike gymnosperms, the male gametes in the angiosperms are reduced to three cells
• Unlike the gymnosperms, the angiosperm seeds develop inside the ovary, ultimately becoming fruits
• The female gametophyte is reduced to seven cells with eight nuclei in angiosperms
• Angiosperms contain a unique endosperm within their seed that has triploid cells. This endosperm forms after the first fertilisation before the division of the zygote
• Angiosperms have a true vascular system with true vessels and companion cells
• Angiosperms have complex root systems

Classification Of Angiosperms 

Depending upon the seed structure, the angiosperms are classified into two types:

• Monocot: The monocots are distinguished by the presence of a single cotyledon in the seedlings.The arrangement of the flower parts in three- or six-fold symmetry and veins running parallel to the length of the leaves in monocots. Example: orchid and palm

• Dicots: The developing shoots of dicots, also known as eudicots, have a pair of cotyledons. The veins form a large network in the leaves of dicots, although the flower section can be observed in four or five pieces. In dicots, the vascular tissues form a ring in the stem, whereas in monocots, the vascular tissues are spread throughout the stem

Reproduction In Angiosperms 

Angiosperms reproduce and expand through a process known as alternation of generations. They go through an asexual and sexual phase cycle. Because it involves the formation of spores, the asexual phase is known as sporophyte generation. The gametophyte generation is the part of the sexual phase that involves the creation of gametes. Male and female gametes develop in the bloom of the plant. Male microspores are found in pollen, where they mature into sperm. In the plant ovary, female megaspores grow into egg cells. For pollination, angiosperms rely on the wind, animals, and insects. Fertilized eggs from seeds, while the ovary of the surrounding plant produces the fruit. Angiosperms are distinguished from gymnosperms by the development of their fruits.

Pollination in Angiosperms 

Self-pollination: Pollen from the same flower lands on the stigma. This will result in producing a seed that will grow into a genetically identical plant.

Cross pollination: Pollen from one bloom lands on the stigma of another plant’s flower. Pollen is carried from one flower to the next by the wind or animals. Pollinated flowers, such as those pollinated by birds, butterflies, or bees, are generally brightly coloured and provide nectar.

The Life Cycle of Angiosperms 

Angiosperms start as seeds made up of a seed coat, a nutrition supply, and an embryo. The seed matures into a sporophyte, which is a flower-producing plant. Flowering is the first step in the reproductive life cycle of angiosperms. Sporangia, structures with spore-producing cells termed sporocytes, are found in stamens and carpels. Spores are produced as eggs or sperm by sporophytes depending on their origin.

Conclusion 

Angiosperms are flower-bearing plants with a true root and shoot system. They have covered seeds inside the ovaries, unlike gymnosperms. They have much lighter pollen than gymnosperms. Hence, pollination occurs through wind, insects, birds, etc.