Double fertilization: Changing frontiers

Concealment of egg by maternal tissues has been an impediment for studies on fertilization in angiosperms. This bottleneck stagnated research on double fertilization for half a century after its discovery by Nawaschin andGuignard in 1898. It was not possible to see what was needed to be seen. The quest for sophisticated tools and techniques, diversification of approach and success in in vitro fertilization brought the period of inaction to an end and incited intense research. Between 1950 and 2000 many questions about double fertilization were answered. Yet, there are more questions and there are more answers. Many of these concern the events and issues never addressed before. Others question such aspects which are being considered fully and finally resolved. The frontiers are changing from time to time.