write a note on pollination, fertilization and embryogeny in cycus.
Answers
Explanation:
Pollination:-
It is the process of transfer of pollen grains from anther to the stigma of pistil.
Pollination is of two types:-
1) Self pollination
It is the transfer of pollen from anther to the stigma of the same flower. It is also called autogamy.
2) Cross pollination
it is the process of transfer of pollen grains from one flower to the stigma of the another flower. It's also called allogamy.
Fertilization:-
It is the most important event in sexual reproduction.
It is the fusion of male and female gametes to form a diploid zygote.
It's also known as syngamy.
The process of fertilization take place outside the female body or inside the female body, on the basis of this, fertilization is divided into two types:-
1) External fertilization.
The fertilization that take place outside the female body in the external medium(water) is called external fertilization.
E.g., most aquatic organism like many algae, bony fish and amphibians.
2) Internal fertilization.
The fertilization that takes place inside the female body is called internal fertilization.
E.g.,Birds, Mammalian, Plant(bryophytes)
Embryogeny in cycus:-
Embryogeny in Cycas is characterized by presence of expanded free nuclear division. The zygote, which is the first sporophytic cell, undergoes free nuclear divisions. The interval between pollination and fertilization is several months in Cycas.