Ls 1 - Sexual Reproduction in Flowering Plants
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To the average person, flowers are of aesthetic, ornamental, social, religious and cultural value. They convey human emotions.
To a biologist, however, flowers are ::morphological and embryological marvels:: and the sites of sexual reproduction. ::📝 Frequently Asked Questions::
Hormonal and structural changes → Differentiation and further development of the floral primordium → Inflorescences (bear the floral buds and then the flowers) → The androecium and the gynoecium differentiate and develop.
AI-generated imagery. Not accurate. Prompt: (Refer to the block in focus)
The androecium is a whorl of the flower, which is made up of Stamens. Now, stamens are the male reproductive units of the flowers. Each stamen is made up of two parts - the anther and the filament. The number and length of the stamens vary with each flower species.
📸 Perspective Corner
What does proximal refer to?
Proximal refers to the closer end of something. In this reference; we call the point where the filament attaches to the thalamus, 'proximal' because it is the part that is closer to the main parts of the plant, like the stem, etc.
Now, if something is called terminal, then it would refer to an "end" of the filament. The word "terminal" can differ with place of usage. Here, we will use the word "terminal" to refer to the further end of the filament.
Filament
The filament is a long and slender stalk that has a terminal structure called Anther attached to it. The proximal end of the filament is attached to the thalamus or the petal of the flower.
Anther
An anther is a bilobed structure (usually) that is terminally attached to the filament. This "bilobed" nature of the anther is usually visible in the transverse section of the anther. Each lobe had two theca, thus they are referred to as dithecous. A longitudinal groove runs lengthwise separating the theca.
The structure of the anther, that we saw before, in effect, makes it a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe.
The microsporangia develop further and become pollen sacs. The pollen sacs run the entire length of the anther and are packed with pollen grains.
Flower
Sporogenous tissue
Germ pore
Autogamy
Egg apparatus
Synergid
Filiform apparatus
Geitonogamy
Xenogamy
Triple fusion
Embryogeny
Cotyledons
Scutellum
Dormancy
Parthenocarpy
Polyembryony
Pre-fertilization events
DOUBLE FERTILIZATION
7-celled and 8-nucleate structure
WIND POLLINATION -
INSECT POLLINATION -
WATER POLLINATION
Pre-fertilization events
Coleorrhiza
Coleoptile
OUT-BREEDING DEVICES
ARTIFICIAL HYBRIDIZATION
AMPHIMIXIS
APOMIXIS
POLYEMBRYO
ARRANGEMENT OF STEPS OF DEVELOPMENT OF EMBRYO
HOMOLOGOUS STRUCTURE OF MONOCOT AND DICOT
Mention one method by which pollen grains can be preserved.
What is the Monosporic development of the embryo sac?
Write the pollination pattern in the - Vallisnaria, Hydrilla, Zostera, and water lily.
Why geitonogamy do is considered genetically autogamy?
Explain the floral reward provided by the yucca plant. 38. How does self-incompatibility restrict autogamy?
Give an account of the significance of double fertilization.
Write the names of different layers of the anther. Mention the role of any one of these.
If the ploidy on the egg is "n, what will be the ploidy of the endosperm of the same plant? Why endosperm is supposed to have nutritive tissue?
What is the fate of floral parts after fertilisation?
Differentiate between parthenocarpy and parthenogenesis. Give one example of each.
Does apomixis require fertilization and pollination? Write any two ways by which apomictic seeds may be developed in angiosperms.