Morphological and histological observation of flower bud differentiation in the bulbs of Lilium pumilum

Anatomic observations with the paraffin sections and scanning electron microscope (SEM) were explored in the terminal bud of Lilium pumilum during flower bud differentiation period to investigate the flower bud development process of L.pumilum bulbs which had come through winter without any special protection. The results showed that morphological characteristics of the stem apex growing point changed from growing cone to reproductive cone in the middle of September. In mid-November, the bottom of inflorescence primordium of the one or two foret primordial had completed the differentiation of perianth primordium, and flower bud continued to differentiate in the following spring. Then the whole inflorescence finished the differentiation before mid-May. The differentiation of inflorescence lasted 8 months, and formed 4-7 flower buds. The flower bud differentiation of L.pumilum could be divided into six stages, which were undifferentiation phase, initial differentiation phase, foret primordial differentiation phase, perianth primordium differentiation phase, stamens primordium and pistil primordium differentiation phase and the whole inflorescence formation phase, respectively.