Abstract:The floral organogenesis of Tsoongiodendron odorum Chun was observed under scanning electron microscope (SEM). The floral primordium is initially circular, along with the edge of which slight concaves occur. The outmost whorl of tepal primordia arises as a result of apical meristem division and the floral primordium then is in the shape of triangle. Two further whorls of tepal primordia arise in spiral acropetal sequence and are alternately arranged. When the innermost whorl of tepal primordia is at the late developmental stage, the foremost stamen primordia arise almost simultaneously in spiral acropetal succession and all of the stamen primordia are ultimately arranged in a triangle-cone form. Late in stamen primordium development, carpel primordia arise as same as the young stamen primordia and grow laterally. Grooves are present on the adaxial side of each carpel and develop into ventral sutures gradually closing up. Concrescence of ventral sutures indicates that T. odorum with advanced characteristics is close to Michelia L..
