Grows from a pollen grain to an ovule provide the best word for the defintion

I believe it's called a pistil or if you want the other version of definition it's called pollination.

Pollen tube

Explanation:

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.