Pollen grains are generally spherical,measuring about

Which of the following has proved helpful in preserving pollen as fossils?

Which layer of the microsporangium helps in protection and dehiscence?

Identify the incorrect statement regarding the sporogenous tissue.

Given below are two statements: One is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A) :$ Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.
Reason $(R):$ Presence of more than one nucleus in the tapetum increases the efficiency of nourishing the developing microspore mother cells.
In light of the above statements,choose the most appropriate answer from the options given below:

In flowering plants,the archesporium gives rise to.......