ADJ (of a vascular bundle) having two strands of xylem (维管束)二原型的 [botany]
The primitive exarch and diarch haplostele with cross-like metaxylem exists in the lower part of CNZ.
在子叶节区下部存在原始的外始式二原型十字形单中柱。
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.
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。
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