References

XII Contents
3 Charles Darwin and the Plant Root Apex:
Closing a Gap in Living Systems Theory as Applied to Plants 37
Peter W. Barlow
3.1 Introduction .................................................................. 37
3.2 The Advancing Root Front and Brain System ...................... 39
3.3 The Location of the Plant Root-Brain................................. 39
3.3.1 Clues from the Transition Zone ............................... 39
3.3.2 Clues from the Polarity of Auxin Flow....................... 41
3.3.3 The Muscular Root-Brain ....................................... 42
3.4 The Anterior Root-Brain.................................................. 43
3.5 Closing a Gap in Living Systems Theory............................. 44
3.6 Conclusions and Future Prospects ..................................... 47
References ............................................................................. 49
4 How Can Plants Choose the Most Promising Organs? 53
Tsvi Sachs
4.1 Introduction: Developmental Selection
of Branch Configurations ................................................. 53
4.2 An Experimental Model Demonstrates Branch Competition 54
4.2.1 The Experimental System ....................................... 54
4.2.2 Stress Increases Competition................................... 56
4.2.3 Unequal Light Conditions....................................... 56
4.2.4 The Rate of Shoot Development and Leaf Removal ..... 56
4.2.5 Hypothesis: Branches Compete................................ 59
4.3 Mechanisms of Competition............................................. 60
4.4 Conclusions and Future Prospects ..................................... 61
References ............................................................................. 62
5 The Role of Root Apices in Shoot Growth Regulation:
Support for Neurobiology at the Whole Plant Level? 65
Peter M. Neumann
5.1 Introduction .................................................................. 65
5.2 The Comparative Need for Rapid Neurobiological Activity
in Animals and Plants...................................................... 66
5.3 Plants That Manage Without Roots, Root Apices
and Vascular Tissues ....................................................... 67
5.4 Do Plant Shoot Responses to Environmental Stresses
Require Rapid Root-to-Shoot Signaling? ............................ 69
5.5 Conclusions and Future Perspectives ................................. 72
References ............................................................................. 72