Question

what is the meaning of 60% of angiosperms, pollen grains are shed at tis 2- celled stage. in the remaining species, the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage)

Answer 1

The meaning is that: if we considers in terms of percentage than in 60 % of the angiosperm the pollen grain are shed at 2 cell stage (consisting of generative and vegetative cell) as the cell division stops at this stage. In remaining (i.e. 40%) of the angiosperm the generative cell divides mitotically to give rise to the two male gametes and vegetative cell before pollen grains are shed (3-celled stage).