There are usually horizontal rather than the slanting end walls of tracheids.Vessel elements have lignified secondary cell walls and at maturity lack a living protoplast.是什么意思_There are usually horizontal rather than the slanting end walls of tracheids.Vessel elements have lignified secondary cell walls and at maturity lack a living protoplast.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句