Once a pollen grain comes in contact with the stigma, a part of the pistil in female plants, a chemical reaction causes the pollen grain to swell and to grow a tube that reaches down to the ovule.
Sattudes emastaime emakas paiknevale emakasuudmele, hakkab tolmutera keemilise reaktsiooni toimel paisuma ning temast kasvab välja tolmutoru, mis tungib seemnealgmesse.