Seeds, when compared to spores, have distinct advantages due to their hard outer shells and internal structures called endosperms, which provide essential nutrients for enclosed seedlings. Seeds are found only in flowering plants and gymnosperms. They contain embryos deep within their centers, which are surrounded by a sack of nutrients and minerals enclosed by a tough protective outer shell that protects the growing seed from predation and life-threatening exposure to the elements.
The hard outer shells of seeds are perhaps their most valuable assets. Seed coats help protect the growing seedlings from damage caused by farm equipment and machinery, desiccation and predation by bugs, insects and birds. The shells also protect against potentially harmful conditions such as wind, heavy rain, frost and extreme heat. These hard outer shells are also quite helpful in protecting species located in fire-prone areas: unlike spores, which wilt and die in high temperatures, seeds protect their inner embryos from destruction during fires, enabling them to safely remain dormant and continue growing. The endosperms in seeds are also important contributors to the growth and success of the enclosed embryo. Endosperms, much like human wombs, supply seedlings with the nutrients and minerals they need to fully grow and develop.