Abstract: 1. Flowering of Ph. vivax seems to be related to the age of development rather than to the external factors such as soil fertility, climatic conditions, silvicul-tural practices etc.2. After gregarious flowering, culms and their connected rhizomes soon become withered completely. In the case of sporadical flowering, however, some new small culms can be developed from some living buds of still alive rhizomes and initiate new buds at their rooted nodes underground. These newly formed culms still flower mostly, but some buds of their rooted nodes develop into new rhizomes known as "rejuvenating rhizomes" from which some new culms sprout again. The new culms produced may grow normally without flowering. As a result of repeatedly producing new culms and new rhizomes, vegetative rejuvenation of a sporadical flowering stand can be expected.3. Bioassay of leaf extract from flowering bamboo stands show that the growth inhibitory substance predominated in both flowering and unflowering culms, and the GA-like substance activity was only found in the unfolding leaves of flowering culms.4. Transplanting of still alive rhizome sections (30~50cm) can accelerate the process of rejuvenation markly, treating the rhizome sections with 100 ppm GA3 before transplanting proves to be favourable to rejuvenation.