structure of Stamen

1. STRUCTURE OF STAMENAND
MICROSPOROGENESIS
Paper –II Sem- III
Dr. Vasanta I. Kahalkar
Assistant Professor
M. G. Artrs, Sci. & Late N. P. Com.
College, Armori

2. STRUCTURE OF FLOWER

3. STRUCTURE OF STAMEN
• Anther- It is a Bilobed tetragonal oblong knob like
fertile part of stamen
• 1 Biolobed 2. Dithecous 3. Tetrasporangiate or Tetra-
microsporangiate

4. • Stamen is the male part of the flower which is
composed of a long filament and an anther
attached to its tip.
• The anther is a bi-lobed structure. Each lobe
contain two pollen sacs.
• The pollen sacs contain pollen grains. The pollen
grains are nourished in the pollen sacs and when
they mature they are liberated out of the sac.
• The pollen grains are very minute structures, which
appear as a powdery mass and can be found in
different size and shapes.

5. INTERNAL STRUCTRE OF ANTHER AND
MICROSPOROGENESIS

7. Internal structure of Anther
• Wall of the anther: The anther wall consists of four layers. These are epidermis,
endothecium, middle layers and tapetum.
• Epidermis: This is the outermost layer. It is only one cell in thickness.
• Endothecium: This layer is situated just below the epidermis. It is a single layer
of radially elongated cell with fibrous thickening. Because of the presence of
fibrous thickenings, the endothecium is also called fibrous layer. In between
these cells, a few cells without thickening are also present. These thinned wall
cells collectively form the stomium or line of dehiscence.
• Middle layers: The middle layers consist of three to four layers of thinned wall
cells. These layers are situated below the endothecium. These layers generally
degenerate to provide nourishment to the growing microspore mother cells.
• Tapetum: Tapetum is the innermost layer of the wall and is multinucleate. The
tapetal cells provide nutrition to the developing microspores. Tapetum secretes
both enzymes and hormones. Tapetum is of two types-Secretory or glandular
tapetum.and amoeboid or plasmodial tapetum. Pollen chamber: The pollen
chamber forms the central cavity of anther lobe. The process of
microsporogenesis takes place in the pollen chamber

8. Microsporogenesis
• Microsporogenesis :- The process of formation of
pollen grain/microspore from sporogenous tissue is
called microsporogenesis.
• The primary sporogenous tissue enlarge as grows
anther mature. It behave directly as microspore mother
cell/ mmc and undergoes reduction divission or
meiotic division & form 4 pollen grain known as
pollen tetrad.
• The wall formation during cytokinesis of pollen tetrad
varies different species. It is two types-
• 1. Successive type
• 2. Simultaneous type

9. Microspore tetrad
• The arrangement of microspores varies with
species. It may be tetrahedral, isobilateral,
decussate, linear or T-shaped

10. THANK YOU