直根：垂直向下生长的宿存主根。

Taproot A persistent primary root that grows vertically downward.

youdao

垂直向下生长的宿存主根。两年生的植物常具有可以储存养料的肥大直根，如：胡萝卜。

Taproot a persistent primary root that grows vertically downward. Swollen taproots used for food storage are common in many biennial plants, such as carrot (Daucus carota).

youdao

冰凉花属于宿根植物，其根几乎终生为初生结构。一年生苗直根系的主根和侧根的初生木质部均为二原型。

Adonis amurensis is perennial herb, Its roots are nearly primary structure in the whole life, Primary Xylems of main root and lateral roots of one year seedling are diarch.

youdao