Vascular plant hybrids are numerous and constitute an important feature of our vegetation, but all too often they have been neglected by botanists. Some hybrids between native species are rare, sterile and ephemeral, but others reproduce vegetatively or by seed and have spread beyond the areas where their parents coexist. In addition, numerous hybrids have escaped from gardens to become established in the wild. Interspecific hybridisation is particularly significant as it represents a major evolutionary pathway in flowering plants; frequently it alters the characteristics of both native and alien taxa and it generates new species. The hybrid flora of the British Isles has been studied in more detail than that of any other region, and it therefore provides an ideal opportunity to study the occurrence of hybrids in wild vegetation.
Hybrid Flora of the British Isles provides detailed accounts of the 909 hybrids reliably recorded in the wild in the British Isles. Identification notes are provided for each of these hybrids, their habitats are outlined and detailed accounts of their distributions provided, with notes on the discovery of many hybrids. Novel maps illustrate the records of the commoner hybrids in relation to those of their parents. Known chromosome numbers are given for each hybrid and its parents, and information is provided on the hybrid's fertility/sterility and its capacity for vegetative reproduction. Experimental and molecular studies of the hybrids in the British Isles and elsewhere in their ranges are summarised. Briefer notes are given on a further 156 hybrids, including some which are erroneously or doubtfully recorded and others which might potentially occur as escapees from cultivation. There is an extensive bibliography of almost 3,000 references.
Hybrid Flora of the British Isles is an essential work of reference for botanists seeking to identify hybrids in the field, for evolutionary biologists investigating the significance of plant hybridisation or its contribution to the spread of introduced plants, for conservation biologists seeking to protect our biodiversity, and for all those teaching about these topics. It both summarises existing knowledge and highlights some significant gaps in that knowledge which need to be filled by future research.
As Professor Richard Abbott says in his Foreword, "This remarkable book will be an essential reference for all British and Irish botanists who have an interest in hybrids. No other book of its kind exists for other parts of the world and consequently Hybrid Flora of the British Isles will surely set the standard for future hybrid floras".
The authors emphasise that this book is not a supplement to or second edition of the 1975 book Hybridization and the Flora of the British Isles, written by Clive A. Stace, but rather a replacement of it. Since 1975, the number of spontaneous hybrids recorded in the wild in Britain and Ireland has risen from 626 to 909, an increase of approximately 45%. In addition, much more has been discovered about many of the hybrids previously described in 1975. 5. It was realised, therefore, that an updated and expanded treatment of hybrids in Britain and Ireland was overdue, and this led in turn to the writing of the current Flora entirely devoted to hybrids.
"[...] Occasionally books come along that are instant classics; this is one of them."
– Peter Thomas, BES Bulletin 46(4), December 2015
"[...] This magnificent production offers a challenge to recorders to get to know hybrids better and to keep their eyes peeled for them in the field. As a standardsetter it is unique: there is evidently no equivalent from any other country in the whole world."
– Peter Marren, British Wildlife 26(6), August 2015