Abstract: Iris is one of the most famous ornamental in the world, to learn the mechanism of flower bud differentiation in Iris, we chose the Iris germanica cv. Lovely Again as material, the process of flower bud differentiation was observed under the scanning electron microscope (SEM). The results were as follows: The process of flower bud differentiation can be divided into six stages from the beginning of flower bud differentiation, i.e., inflorescence initiation, outer perianth initiation, stamen initiation, inner perianth initiation, pistil initiation, and beard hairs initiation. Total soluble sugars content was measured by Anthrone Reagent, amounts of protein was mensurated by Commassie Blue G-250, the samples were taken from the three different parts of plant body during the second floral bud differentiation period, apical bud, rhizome and leaf, respectively. The results were as follows: (ⅰ) Total soluble sugars content was highest in the early flower bud differentiation stage, and the relationship of soluble sugars content among the three different parts was: highest in rhizome, followed by the leaf and apical bud; (ⅱ) The amounts of soluble proteins increased during the early initiation stage and then decreased, the maximum of protein content occurred at the early stage of inflorescence initiation.

Key words: Iris germanica cv. Lovely Again, Floral bud initiation, Morphology, Total soluble sugars, protein