Seed coat

Definition

The seed coat is the protective outer layer of a seed that encases the developing embryo and stored nutrients. This structure plays a critical role in the survival and development of seed plants by safeguarding the embryo from physical damage and desiccation, while also facilitating the seed's dispersal and germination processes.

5 Must Know Facts For Your Next Test

1. The seed coat is derived from the ovule's integuments and can vary in thickness, texture, and permeability, adapting to different environments.
2. In some species, the seed coat can be hardened or have chemical properties that prevent premature germination until environmental conditions are favorable.
3. Seed coats can also have specialized adaptations, like hooks or wings, to aid in wind or animal dispersal.
4. Certain seed coats are impermeable to water or gases until specific conditions trigger them to break down or become permeable during germination.
5. In gymnosperms, the seed coat is often more fibrous and less protective than in angiosperms, reflecting their different reproductive strategies.

Review Questions

• How does the structure of the seed coat contribute to the survival of the embryo in varying environmental conditions?
  • The seed coat provides essential protection to the embryo against physical damage and environmental stresses like desiccation. Its thickness and impermeability can vary among species, allowing it to adapt to specific environments. This adaptation ensures that seeds remain viable during unfavorable conditions until they encounter suitable environments for germination, enhancing the chances of successful plant establishment.
• Discuss the role of the seed coat in facilitating seed dispersal mechanisms and its impact on plant population dynamics.
  • The seed coat plays a significant role in seed dispersal by providing structural adaptations that enable various dispersal mechanisms. For example, certain seeds have coats that are designed for wind dispersal with wings or hooks for attachment to animals. This ability to disperse seeds effectively allows plants to colonize new areas, reduce competition with parent plants, and adapt to changing environments, ultimately influencing plant population dynamics and genetic diversity.
• Evaluate how variations in seed coat characteristics between gymnosperms and angiosperms reflect their evolutionary adaptations and reproductive strategies.
  • Variations in seed coat characteristics between gymnosperms and angiosperms illustrate their distinct evolutionary adaptations. Gymnosperms typically have thinner and less protective seed coats, which align with their reproduction through exposed seeds on cones. In contrast, angiosperms have developed thicker and more robust seed coats that enhance protection and support various dispersal methods. These differences showcase how each group has adapted their reproductive strategies to maximize survival and successful propagation across diverse ecological niches.

Related terms

endosperm:

A tissue within the seed that provides nutrition to the developing embryo, often rich in starches, oils, and proteins.

germination: The process by which a seed develops into a new plant, beginning with the sprouting of the embryo after dormancy.

dispersal: The process by which seeds are spread away from the parent plant, allowing for colonization of new areas and reducing competition.