Which seeds have the hardest coats?

Why do seeds have hard seed coats?

• Answer:

  1. prevents the embryo from dehydration 2. protects the embryo from physical/ mechanical damage 3. protects the embryo from insects as well as bacteria and fungal infections 4. protects the embryo during seed dispersal: e.g. protects against the damage of stomach acid when seeds are eaten by animals. The seed coat or testa is a protective covering that forms around the fertilized ovule.The multicellular seed coat is composed of sclerenchyma cells with very thick cell walls. The coating is normally hard and water resistant, and is formed in the ovary shortly after fertilization from the integument. The primary function of the testa is protection, but it also plays a significant role in seed dispersal; the thickness of the coating varies from species to species, and has to be broken down (or partially decomposed) for water to be able to reach the seed and initiate germination. This provides a delay in germination during which time the seed is hopefully moved further from the parent plant - thus reducing competition between the plant and "extending the range" of the species. Once the correct conditions have been met for germination the seed coat will start to absorb water, soften and eventually split as the embryo inside starts to absorb water, swell and germinate.