Crop-weed complexes consist of crops, modified for human requirements and adapted to man-made habitats, their wild ancestors and other close relatives, and intermediate weeds. A key aspect in these complexes is the possibility of gene flow between any two of the three mentioned elements. Several models of ancestry of crop and weed from their wild ancestor have been postulated. The structure of crop-weed complexes can be studied by using either phylogenetic or phenetic methods, or by using a combined approach. For all methods morphological, electrophoretic and molecular data can be used. These experimental approaches are discussed by means of examples from a range of genera, including Lactuca, Capsicum, Helianthus, Sorghum, Zea and Allium. Further crop examples of which the status as part of a crop-weed complex is not clear are taken from three groups of domesticated plants, i.e. pulses (Leguminosae), ornamentals and woody plants. The domestication scenario of many ornamentals, which consist of genetic information obtained from a range of different relatives (compilospecies) is referred to as the Tulip model. Every level of gene flow can be found between crops and their weedy and wild relatives ranging from absolute reproductive isolation to unrestricted outcrossing.

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Acta botanica neerlandica

CC BY 3.0 NL ("Naamsvermelding")

Koninklijke Nederlandse Botanische Vereniging

L.W.D. van Raamsdonk, & L.J.G. van der Maesen. (1996). Crop-weed complexes: the complex relationship between crop plants and their wild relatives. Acta botanica neerlandica, 45(2), 135–155.