胚根鞘

例句：

1. 1. The plant's seed coat, also known as the seed coat or seed sheath, is a protective layer surrounding the embryo.
   植物的种皮，也被称为种子外皮或种子鞘，是包围胚芽的保护层。
2. 2. During germination, the outermost layer of the seed coat breaks down to release the embryo.
   在发芽过程中，最外层的种皮破裂，释放胚芽。
3. 3. The seed coat plays a crucial role in protecting the embryo during germination.
   种子外皮在发芽过程中起着保护胚芽至关重要的作用。