The comparative study on the botanical characters and root alkaloid content of Madagascar Periwinkle showed that the white with red spot flower variety derived from Bangkok R(,1), the pink flower variety derived from Trat P(,3) and the white flower variety derived from Nakhon Pathom W(,1) contained the maximum (1.3249 %), moderate (0.8711 %) and the minimum (0.3343 %) root alkaloid content, espectively. These varieties did not differ significantly in dry root weight. Plant height and number of branching nodes per plant of the pink flower variety P(,3) and white flower variety W(,1) were similar but these characteristics of the white with red spot flower variety R(,1) were lower. The corolla limb of R(,1), P(,3) and W(,1) showed mostly overlapped, highly overlapped and partially overlapped corolla limb, respectively. Autotetraploid progenies were different from the diploid progenitors in only the overlapped corolla limb, broader leaf, higher root dry weight, less number of branching nodes and seeds per follicle and shorter follicle. The study on the inheritance of the corolla colors was investigated employing phenotypic ratio of the F(,1) and F(,2) progenies derived from the parents carrying three types of corolla color. It could be concluded that the corolla color was controlled by two loci of genes with epistatic interaction. The genotypes of the pink, white and white with red spot varieties should be C_L_, C_ll and ccL_, respectively.