Domesticated plants are essential for agriculture and human societies. Hence, understanding the processes of domestication will be crucial as we strive for more efficient crops and improvements to plants that benefit humankind in other ways. Here, we study the ornamental plant Sinningia speciosa, and reveal that despite the incredible variety found in domesticated varieties (e.g., in flower colour and form), they are all derived from a single founder population near Rio de Janeiro, Brazil. Knowledge of the domestication of horticultural plants is scarce and given its small, low‐complexity genome, and ease of cultivation, we suggest that S. speciosa is a good model for studying genomic variation during domestication.