A Tropical, Gregariously Semelparous Bamboo Shows No Seed Dormancy

Seed dormancy may be disadvantageous for gregariously semelparous plants because it disrupts the high levels of reproductive synchrony necessary for success. Alternately, it may provide a bet-hedging option for an otherwise 'all eggs in the one basket' reproductive strategy. Rapid germination of seeds upon hydration has been demonstrated for a range of tropical, semelparous bamboos, but the fate of seeds that failed to germinate promptly has been inadequately investigated. We demonstrate prompt germination of seeds upon hydration and the absence of a dormant seedbank in a long-lived, gregariously semelparous bamboo, Bambusa arnhemica, from monsoonal northern Australia. However, we refute the suggestion that seed dormancy is necessarily maladaptive in a gregariously semelparous plant. Rather, caryopsis dormancy may not be possible in a seasonally moist tropical climate. Given an inability to adjust or bet-hedge their germination, bamboo germinants must cope with the vagaries of the monsoonal climate, a factor that may contribute to the general restriction of bamboos to regions with higher rainfall. � 2007 The Author(s).