【摘要】 观察了枣树茎中原形成层到形成层的转化过程。距茎端0．5mm处，节间开始伸长之前，横切面上4—5个原形成束及束间的分生组织组成原形成层环。径向切面观，原形成层环呈现出较均一的结构。随着节间开始伸长，由于原形成层细胞发生假横向分裂，出现了长短两类细胞，长细胞多数端壁倾斜，短细胞多数端壁平截。以后，长细胞发育为纺缍状原始细胞，短细胞发育为射线原始细胞，部分射线原始细胞可以伸长井侵入生长而转化为纺缍状原始细胞。在节间伸长将停止时，此种转化基本完成。喜树为非叠生形成层，纺缍状原始细胞和射线原始细胞都有多核现象发生。更多还原

【Abstract】 Observations were made on the process of transition from procambium to camhiumin the shoots of Camptotheca acuminata Decne. Before intrenode elongation takes place,at the level of 0. 5 mm below the tip of the shoot apex,four or five vascular bundles andmeristematic cells from a procambial cylinder. In the tangential view, the procarnbialcylinder shows a rather homogeneous structure. Following internode elongation, shortand long cells appear because of pseudo--tranverse division. Most of the long cells havetapering end walls and the short cells transverse end walls. The long cells become thefusiform initials and the short cells,the ray initials. Some of ray initials elongate tointrude between adjacent cells and change into fusiform initials. When internode elongationnearly stops,the transition almost completes. The cambium of Camptotheca acuminata isnon--stratified cambium. Both the fusiform initials and the ray initials are multinucleate.更多还原