Chapter editor: Rana Munns
Contributing Authors: JS Boyer1, ME Byrne2, R Munns3
1University of Missouri, Columbia, USA; 2School of Biological Sciences, University of Sydney; 3School of Agriculture and Environment, University of Western Australia
With acknowledgements to authors and editors of Chapter 7 of Plants in Action, 1st edition (BJ Atwell and CGN Turnbull)
Seeds germinate, shoots and roots develop, then plants flower and set fruit. Reproduction can occur sexually or asexually. This is the essence of plant life cycles – an alternation of vegetative and reproductive phases – and applies equally well to ephemeral annual species as to centuries-old trees.
In this chapter we show how the vegetative plant axis develops, and the transition to flowering or formation of asexual propagules occurs. Growth occurs by cells in the apical meristems dividing and subsequently enlarging, and taking shape. These are the “growth zones” and occur at root tips of all plants and in different parts of the shoot in monocots and dicots. Plant water status is important: a minimum turgor is necessary for cell growth, but the rate, longevity, and direction of cell growth is regulated by complex processes of signalling. The essential role of the cell wall in controlling growth rate, cell shape, and organ morphology is emphasised.
This Chapter explains the process of vegetative growth and the transition to reproduction. Chapter 8 presents the environmental signals that influence these developmental patterns, allowing optimisation and synchronisation with seasonal cycles of fluctuating climate.