“The fad for Polygonum will fade away!”: historic aspects of the propagation and success in France of the Reynoutria complex based on archives

ABSTRACT

Japanese Knotweeds were introduced by man during the 19^th century in Europe, where they hybridized and formed a species complex now considered as “invasive”. On the basis of many herbarium specimens, the literature and archive documents, we describe the history of their discovery and introduction in France. The circumstances of their hybridization are given, as well as the reasons for the spread of the complex composed of both taxa and their polyploid hybrids. We show that after its discovery by Von Siebold, Reynoutria japonica was introduced as a single male-sterile clone in Lorraine during the early 1850s, whereas R. sachalinensis was discovered by both the French and Russians and subject to successive introductions. Our study reveals that at the end of the 19^th century, these Asiatic Knotweeds became very popular among horticulturists and botanical gardens. Their cultivation in sympatry has led to the production of their hybrid R. x bohemica, as well as interspecific hybridizations and introgressions with parental species, leading to considerable genetic diversity, escape and naturalisation.

KEYWORDS:

• Japanese knotweed
• France
• invasive plant
• Reynoutria
• herbaria
• interspecific hybridisation

Acknowledgments

We would like to thank Frédéric Danet and Isabelle Perrodin of the Jardin Botanique de Lyon, Caroline Loup of the herbier de l’Université de Montpellier, Tristan Vuillet from Archives municipales de Lyon, Didier Morisot of Université Montpellier I, Alain Soubre of Jardin Botanique de Clermont Ferrand, Henri Hours, Director of the Archives départementales du Puy-de-Dôme, Maud Leyoudec and Jérôme Jaillet of the Musée Anne de Beaujeu & Maison Mantin, Gisele Archipoff of herbier de l’université de Strasbourg, Audrey Chambet of the herbier de l’Université de Rennes 1, Carine Denjean and Guy Seznec of the Jardin Botanique de Nancy, Paul Seimandi of the Jardin botanique Henri Gaussen, Philippe Richard of the Jardin botanique de Bordeaux, Antoine Sébastien of the Jardin botanique du Grand Nancy, and Hervé Bulé President of the Société d’Histoire Naturelle de la Moselle. We also thank the herbariums of Aix-Muséum d’histoire naturelle; Aix-Marseille université; Angers - Muséum des sciences naturelles; Aurillac - Muséum des volcans; Autun – Musée d’Histoire Naturelle (AUT); Avignon – Musée requien (UN V); Besançon – Muséum d’Histoire Naturelle nde Bensançon (BESA); Clermont-Ferrand - Université Blaise Pascal; Limoges - Université de Limoges; Orléans - Muséum; Paris - Muséum national d’histoire naturelle; Rodez - Société des lettres, sciences et arts de l’Aveyron (SLA); Soual – Conservatoire Botanique Pierre Fabre (CBPF); Toulon-Muséum d’histoire naturelle; Toulouse – Jardin Botanique; Tours – Université François Rabelais; Verrières-le-Buisson – Herbier Vilmorin (VIL). We are also grateful to Soraya Rouifed, Evelyne Martel and Philippe Heizmann for their assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Mélanie Thiébaut

Dr. Mélanie Thiébaut For this study, Mélanie Thiébaut was the specialist for herbaria, archives, and all literature searches, as well as historical aspects.

Sébastien Nicolas

Sébastien Nicolas made the preliminary research in literature and herbarium specimens.

Florence Piola

Florence Piola was the specialist of Reynoutria complex, its hybridization and introgression processes, and the identification of the different taxa found on herbarium sheets.