The common trumpet tree, Catalpa bignonioides, is the original form of this small, round-crowned tree. If left unpruned, it forms an almost perfect spherical crown, which it retains into old age. It does not tend to develop an elliptical crown shape as much as, for example, the globe maple (Acer platanoides 'Globosum'). 

• Origin: grafting of Catalpa bignonioides (trumpet tree)
  
  
• Growth height: 3–5 meters with standard grafting; up to 10 meters if the grafting point is set higher
  
  
• Leaves: significantly smaller than the species; heart-shaped to triangular-ovoid; up to 15 cm long; fresh green; light yellow autumn color; early deciduous
  
  
• Flower: does not usually flower, but if it does, then in June–July
  
  
• Fruit: very rare
  
  
• Soil/location: partial shade to sun; as windless as possible; highly tolerant of drought, heat, and urban climates