ABSTRACT
Clonal crops are found in diverse plant families and morphological categories (macro-algae, herbs, vines, and trees). Debates concerning the evolution and domestication of clonal crops are introduced with reference to Actinidia, Colocasia, Houttouynia, Manihot, Nelumbo, Saccharum, Solanum and other taxa. Key concepts considered include intergenerational breeding between clones, archetypes and ideotypes as targets for conscious selection, and anti-domesticates: clonal plants that have not been domesticated despite being widely used (Arundo, Pteridium, Pueraria, Typha). Intergenerational breeding by clonal plants suggests a cumulative, endlessly-compounding exponential increase in combinatory possibilities for parent and offspring generations. Such increase would follow, roughly, a double exponential function, and leads to the suggestion that the main gene pools for clonal crops may exist in previously unrecognised, physical convergence zones with very high genetic diversity, or hyper-diversity. Individual clones of some taxa may live for thousands of years, or more, so some living clones within clonal crops might represent ancient domesticates that predate the known archaeological record of agriculture. Previous general models of crop domestication are discussed, and three contrasting models are outlined for clonal crops: the gathering pathway, a simple commensal pathway, and a complex commensal pathway with and without hybridisation. Research on invasion biology has much to offer for understanding clonal crop origins. Limiting factors for understanding clonal crops are the survival and sampling of wild relatives and crop diversity in the field. Baseline ecogeographic surveys are needed to design effective strategies for historical research on clonal crops, and for conservation purposes.
