Question

Plant which prevent both autogamy and geitonogamy are
A. Castor
B. Maize
C. Date palm
D. Cucumber

Answer 1

Hint: The process of autogamy and geitonogamy are a type of pollination and in this pollination occurs on the same plant. The plant which produces both male and female flowers is the correct option for this question.

Complete answer:
If we discuss the definition of autogamy and geitonogamy, then autogamy is when pollen of a flower lands on the stigma of the same flower and in geitonogamy the pollen from male flower lands on the stigma of another flower of the same plant. So clearly, we can see that cross pollination is not occurring in any of the processes.
The plants can be of two types, dioecious plants having only one type of flower or monoecious which have both types of flower i.e. male and female. Autogamy and geitonogamy can occur in monoecious plants easily as they have both male and female flowers but it cannot happen in dioecious plants as they have only one type of flower. Also, the process of autogamy can be seen in the monoecious plants having bisexual flowers.
So, form the given option of plants if we check that which plant is dioecious and which plant is monoecious then we can have the answer. First is castor, The castor plant is known to be monoecious and the flowers produced by the plant are unisexual. So, geitonogamy can be observed in the castor.
The other option is the maize where the plants are monoecious along with the production of bisexual flowers. So, autogamy and geitonogamy both can be observed in the maize plant.
Next is the date palm plant where the plant is dioecious and the flowers produced are unisexual. So, the chances of autogamy and geitonogamy are near to zero.
The last option is the cucumber where the plant is monoecious and the flowers are unisexual. So, only geitonogamy can be observed and no autogamy is reported.

Therefore, the correct answer is the Option C.

Note:
Though the plants which have only bisexual flowers and are monoecious undergo geitonogamy to fertilize and pollinate themselves, these plants can also undergo cross pollination where they can transfer pollens from one plant to other but it is not seen and the plants usually save their resources to achieve cross pollination.