A Randomized Complete Block Design (RCBD) study was performed for characterized on morphology and anatomy of 5 assessions of G. oppositifolius(RĐ1-RĐ5) collected in 5 provinces in Vietnam. The results showed that all assessions have similar morphological structures (roots, stems, leaves, flowers, fruits, seeds), and anatomical structures (roots, stems, leaves). But there hadsome different characteristics in adult stem color (RĐ1, RĐ2, RĐ4, RĐ5 are reddish-brown, RĐ3 is yellow-green); leaf color (RĐ3 was light green, RĐ5 was dark green, RĐ1, RĐ2, RĐ4 were green); RĐ3 assession hadthe highest values of root and leaf size (the root number was 14.60 roots/plant; the leaf length and leaf width were2.33 ± 0.02cm and 1.00 ± 0.06cm, respectively), RĐ5 assession hadthe smallest values of leaf size (the leaf length and leaf width were 1.80 ± 0.01cm and 0.51 ± 0.05cm, respectively). Anatomically, the size of the parenchyma in the stem, the libe bundle in the roots, the stem, and the main leaf veins of the RĐ3 assession hadthe largest sizes. Whereas, the RĐ5 hadthe highest value of leaf thickness (palisade mesophyll thickness was 277.8 ± 6.8µm and spongy mesophyll thickness was 198.9 ± 10.3µm).