Flower development and pistil receptivity in Sinocalycanthus chinensis and Calycanthus floridus var. oblongifolius

The flower development process and pistil receptivity of Sinocalycanthus chinensis and Calycanthus floridus var. oblongifolius were studied by macroscopic observation and using an in vivo pollen germination method. Flower development stages，consisting of a）small flower buds，b）large flower buds，c）relaxed flower buds，d）blooming but anther not dehisced，and e）blooming with anther dehisced，as well as pistil receptivity were almost consistent，whereas pistil development and anther growth differed slightly. Each stage interval was 1 － 2 d with higher temperatures accelerating development. From the small flower bud stage to blooming with anther dehisced，stamens and staminodes were erect，expanding，and then folding. Pistil receptivity period for these two species was 7 － 8 d，and receptivity was strongest at the blooming but anther not dehisced stage. This flower structure and its relative movement facilitated to outcrossing. ［Ch，4 fig. 2 tab. 16 ref.］