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Questions and Answers
What is the function of the outer three wall layers of a microsporangium?
What is the function of the outer three wall layers of a microsporangium?
What is the shape of a typical microsporangium in a transverse section?
What is the shape of a typical microsporangium in a transverse section?
How many nuclei do cells of the tapetum generally have?
How many nuclei do cells of the tapetum generally have?
What is the shape of a typical anther?
What is the shape of a typical anther?
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What is the function of the tapetum in a microsporangium?
What is the function of the tapetum in a microsporangium?
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What is the characteristic of the anther in a transverse section?
What is the characteristic of the anther in a transverse section?
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How many microsporangia are present in a typical anther?
How many microsporangia are present in a typical anther?
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What is the attachment point of the filament to the flower?
What is the attachment point of the filament to the flower?
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Study Notes
Structure of a Stamen
- A typical stamen consists of two parts: the filament (a long, slender stalk) and the anther (a terminal, generally bilobed structure)
- The filament is attached to the thalamus or petal of the flower at its proximal end
- The number and length of stamens vary in flowers of different species
Structure of an Anther
- A typical angiosperm anther is bilobed, with each lobe having two theca (dithecous)
- A longitudinal groove often runs lengthwise, separating the theca
- The anther is a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe
Microsporangium
- The microsporangia are located at the corners of the anther and extend longitudinally throughout its length
- They are packed with pollen grains and develop further to become pollen sacs
- A typical microsporangium appears near circular in outline in a transverse section
- It is surrounded by four wall layers: epidermis, endothecium, middle layers, and tapetum
- The outer three wall layers provide protection and aid in anther dehiscence, while the innermost wall layer (tapetum) nourishes the developing pollen grains
Tapetum
- Tapetal cells have dense cytoplasm and often have more than one nucleus (bi-nucleate)
- The tapetum provides nutrients to the developing pollen grains
Microsporogenesis
- The cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads as the anther develops
- The ploidy of the cells of the tetrad is haploid
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Description
This quiz covers the structure and function of stamens, microsporangium, and pollen grains in flowers. Learn about the filament, anther, and other components of stamens.
