Here, for the first time in a single volume, are all the ideas and techniques developed in the last two decades concerning the manipulation of pollen and pollen tubes in plant breeding and biotechnology.

In Recognition of the Forgotten Generation D. L. MULCAHyl Pollen was long believed to serve primarily a single function, that of delivering male gametes to the egge A secondary and generally overlooked value of pollen is that it serves to block the transmission of many defective alleles and gene combinations into the next generation. This latter function comes about simply because pollen tubes carrying defective haploid genotypes frequently fail to complete growth through the entire length of the style. However, the beneficial consequences of this pollen selection are diluted by the fact that the same deleterious genotypes are often transmitted through the egg at strictly mendelian frequencies (Khush, 1973). Gene expression in the pollen might thus at least appear to be a phenomenon of trivial consequence. Indeed, Heslop-Harrison (1979) rightly termed the gametophytic portion of the angiosperm life cycle, the "forgotten generation." This neglect, however, came about despite subtle but constant indications that pollen is the site of intense gene activity and selection. For example, Mok and Peloquin (1975) demonstrated that relatively heterozygous diploid pollen shows heterotic characteristics whereas relatively homozygous diploid pOllen does not. This was proof positive that genes are expressed (that is, transcribed and translated) in the pollen. 1 Department of Botany, University of Massachusetts Amherst, MA 01003, USA viii However, the implications for pollen biology of even this recent and well known study were not widely recognized.

In Recognition of the Forgotten Generation D. L. MULCAHyl Pollen was long believed to serve primarily a single function, that of delivering male gametes to the egge A secondary and generally overlooked value of pollen is that it serves to block the transmission of many defective alleles and gene combinations into the next generation. This latter function comes about simply because pollen tubes carrying defective haploid genotypes frequently fail to complete growth through the entire length of the style. However, the beneficial consequences of this pollen selection are diluted by the fact that the same deleterious genotypes are often transmitted through the egg at strictly mendelian frequencies (Khush, 1973). Gene expression in the pollen might thus at least appear to be a phenomenon of trivial consequence. Indeed, Heslop-Harrison (1979) rightly termed the gametophytic portion of the angiosperm life cycle, the "forgotten generation." This neglect, however, came about despite subtle but constant indications that pollen is the site of intense gene activity and selection. For example, Mok and Peloquin (1975) demonstrated that relatively heterozygous diploid pollen shows heterotic characteristics whereas relatively homozygous diploid pOllen does not. This was proof positive that genes are expressed (that is, transcribed and translated) in the pollen. 1 Department of Botany, University of Massachusetts Amherst, MA 01003, USA viii However, the implications for pollen biology of even this recent and well known study were not widely recognized.

A century of research on heterostylous plants has passed since the publication of Charles Darwin's book "The Different Forms of Flowers on Plants of the Same Species" in 1877 summarizing his extensive observations and experiments on these complex breeding systems involving genetic polymorphisms of floral sex organs. Since then heterostylous plants have provided a rich source of material for evolutionary biologists and today they represent one of the classic research paradigms for approaches to the study of evolution and adaptation. The present book is the first modern and comprehensive accont of the subject. In 10 chapters it is concerned with the evolution, genetics, development, morphology, and adaptive significance of heterostyly. Broad syntheses of research on heterostyly as well as new theoretical ideas and experimental data are included.

This collection of reviews by leading investigators examines plant reproduction and sexuality within a framework of evolutionary ecology, providing an up-to-date account of the field. The contributors discuss conceptual issues, showing the importance of sex allocation, sexual selection and inclusive fitness, and the dimensions of paternity and maternity in plants. The evolution, maintenance, and loss of self-incompatibility in plants, the nature of 'sex choice' in plants, and sex dimorphism are all explored in detail. Specific forms of biotic interactions shaping the evolution of plant reproductive strategy are discussed, and a taxonomically based review of the reproductive ecology of non-angiosperm plant groups, such as bryophytes, ferns, and algae, is presented. Together these studies focus on the complexities of plant life cycles and the distinctive reproductive biologies of these organisms, while showing the similarities between nonflowering plants and the more thoroughly documented flowering species.

Principles and Practices in Plant Ecology: Allelochemical Interactions provides insights and details recent progress about allelochemical research from the ecosystem standpoint. Research on chemical ecology of allelochemicals in the last three decades has established this field as a mature science that interrelates the research of biologists, weed and crop scientists, agronomists, natural product chemists, microbiologists, ecologists, soil scientists, and plant physiologists and pathologists. This book demonstrates how the influence of allelochemicals on the various components of an ecosystem-including soil microbial ecology, soil nutrients, and physical, chemical, and biological soil factors-may affect growth, distribution, and survival of plant species. Internationally renowned exper†s discuss how a better understanding of allelochemical phenomena can lead to true sustainable agriculture.