Flowering in Bamboo: an Enigma!

The switch to flowering is the most important event in the life cycle of a plant, signaling its commitment to set seed ensuring survival of the species. Effective and efficient pollination leading to seed set requires that all individuals in a population flower together. Environmental cues are the most effective in bringing about simultaneous flowering in populations growing over wide extents of land. However, flowering in certain species of bamboo is intriguing, in that the cues that trigger flowering still remain a mystery. These manifest a cyclic pattern of flowering after long, and sometimes regular, vegetative periods that extend up to even 120 years. All individuals growing over vast expanses of land flower in synchrony along with individuals growing elsewhere far away. This phenomenon of mast flowering or mast seeding is the synchronized flowering and production of seed at long intervals by a large population. In bamboo, the population produces wind-pollinated flowers, sets seed in large quantity and perishes. The seeds regenerate to repeat the life cycle. Thus flowering is related to its life span, similar to that of annuals or ephemerals that flower and set seed only once before perishing. Mast flowering is uncommon in the plant kingdom and even in bamboo, only a few species exhibit this phenomenon. The unpredictable nature of this event has brought about devastations to people whose livelihood depends on bamboo. The growing economic importance of bamboo thus requires the understanding of flowering in this group of plants. Induction of flowering in vitro would be an approach to this solution in the absence of any other mechanism that can be used to trigger flowering in nature.