Revision: Reproduction >> Sexual Reproduction in Flowering Plants CUET (UG) Sexual Reproduction in Flowering Plants

When calyx and corolla are not differentiated, the floral envelope is called the perianth.

Individual members of the perianth are called tepals.

A circular arrangement of floral organs at the same level on the thalamus is called a whorl.

A modified, compressed reproductive shoot of angiosperms bearing sepals, petals, stamens, and carpels, meant for sexual reproduction, is called a flower.

The swollen terminal part of the pedicel on which all floral whorls are arranged is called the thalamus or receptacle.

A flower that has only one reproductive whorl (either androecium or gynoecium) is called a unisexual flower.

• If it has only androecium: male flower
• If it has only gynoecium: female flower
  Example: Papaya

A specialised axis or branch over which flowers are produced or borne in definite manner is known as inflorescence.

A flower that has both androecium (male part) and gynoecium (female part) in the same flower is called a bisexual flower.
Example: Hibiscus

A flower that has a stalk called pedicel for support is called a pedicellate flower.

The structure in flowering plants that develops into a seed after fertilization is called the ovule.

The controlled crossing of selected male and female parent plants to produce genetically superior offspring is called artificial hybridization.

When pollination occurs within the same flower or between two flowers on the same plant, it is called self-pollination.

or

Transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant is said to be self~pollination.

Transfer of pollen grains from the anther to stigma is called pollination.

When pollination occurs between flowers on two different plants of the same species, it is called cross-pollination.

or

Transfer of pollen grains from the anther of a flower from one plant to the stigma of the flower on another plant is called cross-pollination

Union of the second male gamete with two polar nuclei to form endosperm, along with fertilization, is called double fertilization.

• Flower is the main reproductive organ in plants, made up of four whorls—calyx, corolla, androecium, and gynoecium.
• Essential whorls: Androecium (male) and Gynoecium (female);
  Accessory whorls: Calyx (sepals) and Corolla (petals).
• Bisexual flowers have both androecium and gynoecium (e.g., Hibiscus);
  Unisexual flowers have only one (e.g., Papaya).
• Gynoecium contains carpels with ovary, style, and stigma;
  Ovary has ovules, which form the embryo sac by meiosis.

• A typical anther is dithecous, having two anther lobes, each with two microsporangia containing pollen grains.
• Archesporial cells divide to form primary parietal layers (anther wall) and primary sporogenous tissue.
• The anther wall consists of epidermis, endothecium, middle layers, and tapetum; the tapetum provides nutrition to developing pollen.
• Microspore mother cells (2n) undergo meiosis to form four haploid microspore.
• During anther dehiscence, contraction of endothecium causes rupture at the stomium, releasing pollen grains for pollination.

• The ovule consists of a central nucellus surrounded by one or two integuments that provide protection.
• Based on integuments, ovules are unitegmic, bitegmic, or ategmic, depending on the number present.
• The integuments enclose the nucellus leaving a small opening at the apex called the micropyle.
• The ovule is attached to the placenta by a stalk called the funicle; the point of attachment is the hilum, and the basal region is the chalaza.
• During development, the ovule arises from the placenta, and integuments grow around the nucellus to form the mature ovule.