Angiosperm - A complete plant having unique phenomenon double fertilization
Angiosperms or flowering plants are higher plants that occupy top positions in the plant kingdom. An angiosperm is a complete plant bearing fruit and seed, flowers etc.
Angiosperms belong to one of the most diverse and largest extant groups of plants found in the universe. There are about more than 250,000 living species of flowering plants on the earth and they have great diversity. These plants are well developed and have an elaborate process of sexual reproduction in which an egg is fertilized and developed into a seed in an enclosed hollow ovary are angiosperms.
The seeds in angiosperms are found in the flower unlike the gymnosperm. In gymnosperms, the seeds are developed in female strobili or female cones. Male reproductive organs and female reproductive organs are easily distinguished inside the flowers of angiosperms.
The ranges of size in angiosperms varies from Angiosperms from tiny herbs to giant trees. They can acquire size from millimeters to large trees that are over 100 meters tall.
👌👌Remember - The most diverse family of angiosperms are Orchidaceae belonging to the orchid family.
Root systems in flowering plant
The part of the plant that is suspended inside the soil is called the root system. The system includes roots and root hair and their associated structure. The roots provide anchorage to the plant, and absorb water and minerals from the soil with their root hairs.
In flowering plants, Root systems are classified into primary root systems and tertiary root systems.
The primary root systems consist of a taproot which grows vertically downward. Tap root produces various smaller lateral roots that may grow horizontally or diagonally. These are termed as secondary roots.
The main difference between the primary and tertiary root systems is that the primary root remains present in the plant for a very short time and it is replaced by secondary than tertiary root as per the requirement.
Shoot systems in flowering plant
The Aerial part of the plant that bears the leaves and flowers is called the stem. The stems maintain the supply of water and minerals and transport them directly to the leaves, flowers, and plants. The stem of the plant is connected to the root systems for the continuous flow of nutrients through the hypocotyl. The leaves are attached to the stems at the nodes and internodes are the regions that lie in between the two successive nodes. Axillary and dichotomous are the two forms of branching system present in angiosperms.
Leaves in flowering plant
The Leaves are also the aerial part of the flowering plant.The process of photosynthesis take place on the surface of the leaves and thus it appears green in most of the plants
The leaf base, stipules, petiole, and lamina are the parts of the leaf. The stipules are present at each turn of leaf base while the blade and the leaf base are connected with the help of petiole. In Some angiosperms, leaves lack petioles whereas in some leaves, stipules are absent.
Flowers and reproduction in Flowering Plant
Flowers are beautiful and attractive creatures in flowering plants. Male,and female reproductive structures are found inside the flower.
Stamen is male reproductive structure and is made up of two parts Anther and filament. Anthers produce microspores of pollen grains inside the microsporangia.
Pistil or carpel is female reproductive structure and comprises three parts- Stigma, style and ovary. Inside the ovary
Ovule is present. Ovule encloses the embryo sac. Embryo sac has antipodal cells, synergids, egg and polar nuclei.
Pollen grains are transferred from anther to stigma by the pollination. Pollen grains are germinated in the form of a pollen tube and render two male gametes into mature embryo sacs. At embryo sac first male gamete fuse with egg through syngamy and form diploid zygote. Second male gametes fuse with polar nuclei and form triploid primary endosperm nuclei by the triple fusion. This is known as double fertilization. It is the characteristic feature of flowering plants.
After fertilization, zygote is changed into an embryo, and the primary endosperm nucleus is developed into endosperm. In addition to this, ovule and ovary are changed into seed and fruit respectively.
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