In the present study, development of trilobed stem is investigated in Distimake tuberosus (Convolvulaceae) by histological methods. Increase in stem thickness and formation of trilobed stem was achieved by forming crescent shaped successive cambial segments from the pericyclic parenchyma at three equidistant sites. In contrast, the alternate segments of the vascular cambium were functionally less active, dividing leisurely (referred henceforth as functionally less active cambium) and did not form the successive cambium. The newly formed cambial segments divide bi-directionally and produced its derivatives, while functionally less active segment lagged behind. The secondary xylem formed from the functionally less active cambial segments have unique pattern of vessels distribution i.e., wide vessels rare or completely absent. Parenchyma (both, axial and ray) proliferation, formation of ray cambium, functionally inverse cambia, tyloses in fibriform vessels and the occurrence of bordered pits in xylem ray cells are observed in all samples. Root diameter increased by developing concentric rings of successive cambia and maintained a circular outline. Formation of successive cambia on three sides and alteration in stem outline may be associated with protection of conducting elements against stem torsion and internal injury. Formation of conducting elements from the ray cambium and internal cambium suggest rapid and safe conduction of photosynthate, water and mineral elements.

在本研究中，通过组织学方法研究了马铃薯（Distimake tuberosus，旋花科）中三叶茎的发育。茎粗的增加和三叶茎的形成是通过在三个等距位置从周周薄壁组织形成新月形的连续的冈比亚节段而实现的。相反，血管形成层的交替节段在功能上活性较低，悠闲地分开（此后称为在功能上活性较低的形成层），并且不形成连续的形成层。新形成的冈比亚部分双向划分并产生其派生词，而功能上不太活跃的部分则滞后。由功能不太活跃的冈比亚节段形成的次生木质部具有独特的血管分布模式，即，稀少或完全不存在的宽血管。在所有样品中均观察到实质（轴向，射线）增生，射线形成层形成，功能上的逆向冈比亚，纤维状血管中的tyloses以及木质部射线细胞中出现有边界的凹坑。根部直径通过形成连续后倾的同心环而增加，并保持圆形轮廓。在三个侧面形成连续的斜交，并改变茎的轮廓可能与保护传导元件免受茎的扭转和内部伤害有关。由射线形成层和内部形成层形成的导电元素表明光合产物，水和矿物质元素的快速安全的传导。