The wings enable the pollen grain to be blown to an ovule, where it germinates, forming a slender pollen tube through a weakened area of the pollen wall. The pollen tube elongates through "tip extension," penetrating between cells of the host parent. Within the pollen tube, two nonmotile sperm cells are ultimately formed and are conveyed through the tube, keeping pace with tip growth. The pollen tube uses chemotropic signals to determine the final pathway to the egg cell, deep within the ovule, where fertilization occurs.
The pollen wings aid in the dispersal of the pollen grains by wind.
Apr 27th, 2015
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