Filiform apparatus is characteristic feature of:
Synergids are present in the mature embryo sac and are essential for angiosperm reproduction. They have special cellular thickenings at the micropylar tip called filiform apparatus, which play an important role in guiding the pollen tubes into the synergid.
Mature pollen grains contain two cells, the vegetative cell, and the generative cell.
The embryo sac is located in the nucellus. In Citrus and Mango nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into the embryos.
The aleurone layer is located between the seed coat and cotyledon tissue.