protophloem

例句：

1. 1. The plant's protophloem is responsible for transporting waterand nutrients throughout the plant.
   植物的原生木质部负责将水分和养分输送到整个植物体。
2. 2. In the study of plantanatomy, the protophloem plays a crucial role in understandingthe structure and function of the plant's vascular system.
   在植物解剖学研究中，原生木质部在理解植物的血管系统结构和功能方面起着至关重要的作用。
3. 3.The protophloem is alsoknown as the "root" of theplant, connecting the leaves to the restof the plant body.
   原生木质部也被称为植物的“根”，连接着叶子和植物体的其他部分。