Introduction
Angiosperms or flowering plants are most successful plants today as they are the largest class of plants with 13,000 genera and approximately 3, 00,000 species dominating on earth and maintaining the life support system on earth. Most of the economic needs of mankind fulfill by these groups of plants. They have adapted to almost every habitat from mountain tops, rivers, lakes and even deserts.
Angiosperms are vascular plant that reproduce sexually by forming flower. Flower is a reproductive part of plants where pollen grain and ovules are developed and that makes angiosperms distinct from the gymnosperms, where ovules are naked. In angiosperms, the seeds are enclosed within fruit. Flowering plant have efficient system of conducting water and food.
Characteristics
Angiosperms or flowering plants are known for their diverse characteristics. Some important characteristics of angiosperms include:
- Angiosperms produce flowers, which are reproductive structures that attract pollinators and facilitate reproduction.
- Flowering plants undergo alternation of generations in which the sporophyte generation is nutritionally independent and gametophyte is nutritionally dependent on the sporophytes.
- Flowering plants are heterosporous and produce two kinds of spores, microspores (Pollen grain ) and megaspores.
- After fertilization, angiosperms develop fruits that enclose the seeds, aiding in seed dispersal.
- Angiosperms have seeds that develop within the fruit, providing protection and nourishment to the developing plant.
- They possess well-developed vascular systems, including xylem and phloem, which efficiently transport water and food.
- Angiosperms exhibit a wide range of forms, from tiny microscopic Wolffia to large trees of Eucalyptus, adaptively radiating in various habitats.
- Angiosperms employ various methods to facilitate pollination including wind, insects, and birds or bats.
- There is a unique event takes place in the life cycle of angiosperms that is double fertilisation, where one sperm fertilizes the egg, while another forms the endosperm to nourish the developing seed.
These characteristics contribute to the ecological success and diversity of angiosperms, making them the most widespread group of plants on Earth.
Classification of Angiosperms
Angiosperms are classified into two main groups : Monocotyledon and Dicotyledon
Monocotyledon
- These plants have seed with a single cotyledon or embryonic seed leaf.
- The monocots have narrow leaves with parallel venation.
- The flowers parts usually occur in three.
- Monocots have adventitious roots.
- Monocots lack secondary growth.
- Examples are palms, grasses, orchids, irises, onions, and lilies.
Dicotyledons
- These plants have seed with two cotyledons.
- The dicots have broad leaves with reticulate venation.
- Dicots have tap root system.
- The flower parts of dicots usually are tetramerous or pentamerous.
- The stems and roots of dicots show secondary growth.
- Examples are oaks, roses, mustards, cacti, blueberries, and sunflowers.
