英语语法分析

This had similar mercury levels to the phloem.

树皮的汞含量与韧皮部相近。

Primary phloem PHLOEM derived from the procambium in the young plant.

初生韧皮部：指幼嫩植物中来源于原形成层的韧皮部。

Phloem elements and adjacent tissues are the principal feeding sites for most aphids.

韧皮部及其邻近组织是大多数蚜虫的主要取食部位。