SEEDSGymnosperms and Angiosperms

SEEDS

• Plant seeds consist of an embryo which is surrounded by a special seed coat called a testa.

• The seed develops from the zygote formed when one of the 2 sperm nuclei in the pollen tube fertilizes the egg in the ovule.

• When conditions are right, the seed grows or germinates.

• The first part to emerge is the root which breaks through the testa.

• The next part to emerge is the shoot / stem

The parts of the seed:

SEED PART MATURES INTO ADULT PART CALLED THE:

Radicle RootEpicotyl Leaf budHypocotyl StemPlumules Leaf/Leaves

Gymnosperm vs Angiosperm Seed

• Angiosperms: Enclosed inside an overy, usually a fruit.

• Gymnosperms: Bare, not enclosed; found on scales, leaves or as cones.

Gymnosperm vs Angiosperm Seed

Monocot seedExample: Corn seed• Only one cotyledon present in the embryo• Cotyledon is thin and small and lacks food

materials• Endosperm is mostly present as part of the

seed and stores food

Germinating monocot seed

Dicot seed Example: Bean seed

Dicot seedExample: Bean Seed• Two lateral cotyledons are present in the

embryo axis• Cotyledons are fleshy and store food• Endosperm is mostly absent and lacks food

Germinating dicot seed