Complete process of flower development of C. sinense and seasonal distribution of different development stages. A, B First stage of flower development (S1). Flower development starts with the appearance of a floral buttress on the shoot flank that forms a flower primordium (fp). C–E Differentiation of the flower primordia into sepal, petal, lip, and column primordia. F, G Second stage of flower development (S2). The second stage denotes slow elongation of the inflorescence meristem for 3–4 months. H Complete cycle of flowering from vegetative to reproductive phase transition and blooming in the next year. The vegetative growth lasts >2 years and then transition occurs in July. After a short period of flower initiation, the floral buds enter a period of semidormancy that lasts >3 months. Flower development resumes in November and blooming occurs in February of the next year. I Visual display of five stages of flower development (S1–S5). S1 and S2 undergo semidormancy before resuming flower development from S3. S4 represents complete flower formation and S5 denotes fully opened flowers. Lower row shows the vertical dissection of floral bud from S1 to S4, while S5 shows the complete flower with its organs.