In nonwoody plants the primary xylem is the only water-conducting tissue, but in mature plants with secondary growth this function is mostly taken over by the secondary xylem. 在尚未木質化的植物中，初生木質部是唯一的輸水組織，但在具有次生生長的成熟植物中，該功能大多由次生木質部行使。
In nonwoody plants the primary xylem is the only water-conducting tissue, but in mature plants with secondary growth this function is mostly taken over by the secondary xylem. 在尚未木質化的植物中，初生木質部是唯一的輸水組織，但在具有次生生長的成熟植物中，該功能大多由次生木質部行使。
