美洲黑杨维管形成层发生发育的解剖学观察

The Anatomical Observation on the Occurrence and Development of Vascular Cambium in Populus deltoides

利用常规石蜡切片技术，观察研究了美洲黑杨维管形成层的发生和发育，结果表明：（１） 从顶端分生组织至原形成层，以及由原形成层向维管形成层的转化是随着茎的发育逐渐向顶进行的，而且叶迹与维管组织的发育密切相关；（２） 维管形成层为叠生型，并在芽萌动前已开始活动，４ 月中旬进入活动旺盛期，分裂形成的薄壁细胞迅速分化为导管参与构成次生木质部。

The material used for this study was collected December May during 2 successive years (1997～1998)from the branches of apparently healthy Populus deltoides growing on the campus of Nanjing Forestry University,Nanjing, China.The samples were taken from three or four trees at 5 day or monthly intervals.The stem and the shoot were fixed in FAA prepared for anatomical studies.The occurrence and development of vascular cambium in Populus deltoides were studied in serial sections of shoot and stem.The results show as follows:(1)The transition from apical meristem to procambium and from procambium to cambium turn toward gradually the apex of stem in process,and the leaf trace is related to vascular tissues closely.(2)The vascular cambium is non stratified,and begins activity before the budding.It marched into the exuberant activity stage in the middle of April,and the cell which derived from the division of vascular cambium differentiated rapidly into vessel forming metaxylem.