Studies on Weed Species of the Genus Polygonum L.

Summary. Seeds of Polygonum persicaria from several sources, or from plants subjected to in lain treatments, were chilled for varying periods and incubated for a 3‐week germination test period. Populations differed widely in seed weight and to some extent in the response to different periods of chilling. No relationship between this response and the climate of the locality of origin could be found. There was much variation in seed weight and germination behaviour between individual plants within populations. A total of four polymorphic seed categories were observed. The proportions of seeds in the two main categories varied widely between and within populations, and were affected by certain environmental factors. These factors also appeared to affect the degree of inter‐plant variation in seed shape and germination behaviour. Travaux sur les espàes indésirables du genre Polygonum L. V. Variations dans le poids des semences, leur comportement à la germination et leur polymorphisme chez P. persicaria L.