Abstract:The formation of scorpioid cyme, capitulum and floret of Flaveria bidentis (L.) Kuntze was observed under scanning electron microscopy. The inflorescence of F. bidentis was composed of the main axis with three orders branches in a decussate arrangement. Scorpioid cymes (3~6) were developed at the apex of the main inflorescence axis as well as lateral axes. Each scorpioid cyme had 5~15 capitulums which was consist of 4~11 florets. For the floral development process, five petal primordia arose firstly, then five stamen primordia appeared, followed by two carpel primordia. In 2007, florescence of F. bidentis was from late July to late September in Tianjin. In Mid July, the inflorescence primordia and floret primordia were formed and differentiated continually, and approximately 15 days after the initiation of flower bud differentiation, individual floret was well formed.
