| Noun | 1. | genus Gymnosporangium - genus of fungi that produce galls on cedars and other conifers of genera Juniperus and Libocedrus and causes rust spots on apples and pears and other plants of family Rosaceae fungus genus - includes lichen genera family Pucciniaceae, Pucciniaceae - large important family of rust fungi apple rust, cedar-apple rust, Gymnosporangium juniperi-virginianae - rust fungus causing rust spots on apples and pears etc |