Noun | 1. | ![]() rosid dicot genus - a genus of dicotyledonous plants family Rosaceae, Rosaceae, rose family - a large family of dicotyledonous plants of order Rosales; have alternate leaves and five-petaled flowers with numerous stamens Heteromeles arbutifolia, Photinia arbutifolia, tollon, toyon, Christmas berry, Christmasberry - ornamental evergreen treelike shrub of the Pacific coast of the United States having large white flowers and red berrylike fruits; often placed in genus Photinia |