GYNOECIUM
- It is the female sexual organ of a flower.
- Unit- pistil or carpel.
Types-
1. Monocarpellary - flower has only 1 pistil
OR
Gynoecium has only 1 pistil.
2. Multicarpellary- multiple pistils.
Depending upon the fusion of these pistils, multicarpellary has two types-
A. Syncarpous- all carpels are fused together. Eg. Papever
B. Apocarpous- pistils are free.
Eg. Michella.
PARTS OF PISTIL / CARPEL
1. STIGMA
- It forms landing platform for pollen grains.
- Requirement- it should be rough to catch pollen grains.
2. STYLE
- Slender, elongated
- Tube like structure
- Connects stigma to ovary.
- Function- through the style, the pollen tube grow towards ovary.
3. OVARY
- Basal part
- Bulged part
- Cavity- ovarian cavity / locule.
- Inside ovary, placenta is present.
- From placenta, ovules (megasporangium) arise.
Number of ovules in a flower- variable
- Wheat, paddy, mango - one
- Papaya, water melon, orchids - many.
- Trick- fruits with multiple seeds, had multiple ovules in their flowers.
OVULE / MEGASPORANGIUM
STRUCTURE-
1. Funicle/ stalk - connects ovule with the placenta.
2. Hilum- junction of funicle and body of ovule.
3. Nucellus- cell mass, which contains abundant food reserve.
4. Integument- covering of ovule, protects the ovule. Two in number, outer and inner.
5. Micropyle- opening in integument.
6. Chalaza- opposite of micropyle.
MEGASPOROGENESIS
Nucellus (2n) - near micropyler end - a cell differentiate --- megaspore mother cell (dense cytoplasm, big nucleus)
Megaspore mother cell (2n) --- meiosis --- 4 megaspores (n)
Out of there 4 megaspores--
3 degenerate
And 1 remain functional
This one functional megaspore -- female gametophyte / embryo sac (n)
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