Pollen Grains <ul><li>Capsules with specialized cells: </li></ul><ul><li>two sperms cells </li></ul><ul><li>one “tube” cell </li></ul>all three of these cells are haploid half the number of chromosomes for that species
Pollination: when pollen lands on a stigma tube cell grows a tube down through the style and into the ovary
sperm move through the tube and into the ovary
one sperm fertilizes an egg to form a diploid zygote that grows into an embryo plant
the other sperm fertilizes a special cell that develops endosperm
endosperm is food storage tissue that supports the embryo plant inside the seed
From pollination to fertilization can take an hour or days as the amount of time it takes for a sperm to travel through the pollen tube can vary.