Secondary xylem consists of pitted vessels, parenchyma fibers and rays.
次生木质部由孔纹导管、薄壁组织及射线所组成。
The xylem of ferns and conifers contains only tracheids.
蕨类植物和针叶树的木质部仅含有管胞。
Large proportion of xylem benefit to the water transfer.
叶脉中木质部比重越大，越有利于水分的传输。
A merry Xmas to all our readers!
祝广大读者圣诞快乐！
Merry Xmas!
圣诞快乐！