The scanning electron microscope (SEM) and light microscope were used to observe floral primordia initiation, flower bud initiation, and development of flower buds in Camellia japonica and C. sasanqua. Vegetative and flower buds were collected from trees 9-12 year old from February until March in the following year.
Most flower buds of Camellia were derived from floral primordia in vegetative buds (terminal or lateral). Floral primordia appeared more frequently in the terminal bud than in lateral buds, and in mature older plants than in seedlings.
Floral primordia formation occurred in the axils of scales in new buds within 4 weeks in C. japonica and 3 weeks in C. sasanqua during shoot elongation, while vegetative primordia initiated in the axils of leaf primordia prior to bud break.
Flower bud initiation was signaled by the appearance of an apical flattened space with the last three perules (9th-11th) formed around it. Flower bud initiation occurred during 4 weeks in C. japonica, 5 weeks in C. sasanqua after shoot growth ceased. After flower bud initiation, floral parts were initiated rapidly in the following sequence: petals, stamens, pistils, ovules, and pollen. The initiation of each floral stage was separated by an average of 10.5 days in C. japonica and 9.9 days in C. sasanqua. There was no difference in flower bud development between C. japonica and C. sasanqua. The irregular formation of stamens in the double flowering cultivar of C. japonica, and the 4 stigmas, hairs on the ovary and extension of the partly united style of C. sasanqua were observed in the early stages of development of each of these floral parts.
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