All the varieties of tea plant have a constant chromosome number of 2n=30 except a few natural triploids.The clones belonging to the three main races of tea do not show any major difference in their gross morphology and karyotype, although some minor differences existed. The ploidy in the genus Camellia ranges up to hexaploid with 2n=90 though naturally evolved polyploids in tea are rare. Aneuploidy is also reported with unusual chromosome numbers of 2n=32, 33, 38, 42, 58, 59 , 61 and 63. The length oftea chromosomes ranges from 1.28u to 3.44u. The ‘r’ values (ratio of long to short arm) for all the 15 pairs of chromosomes range from 1.00 to 1.91. The meiotic division in teas are regular with 15 bivalents at metaphase I and segregation is regular. Due to the absence of sharp morphological differentiation between the genomes of different Camellia taxa which are mostly primitive and sub-median in nature facilitates the enormous genetic introgression during the entire course of evolution resulting structural and hybrid heterozygosity in the entire germplasm of tea.
Tea is a C3 plant following Rubisco metabolism. Tea plant can adapt well to different terrain and climatic conditions. In general, China type tea can adapt to wide range of soil and climatic conditions than those of Assam type.