100+ Royal Empress Tree Seeds (Paulownia tomentosa) Purple Flowers, Fast Growing! Grow Zones: 5,6,7,8,9 Other Names: Empress Tree, Princess Tree, Royal Paulownia, Purple Foxglove Tree Paulownia tomentosa is a deciduous tree that can grow up to 80 feet tall in the wild. In cultivation, it is often kept trimmed to a more manageable height. The tree produces large, heart-shaped leaves that are green in the summer and yellow in the fall. The tree's most distinctive feature, however, is its beautiful purple flowers that bloom in the spring. These flowers are fragrant and provide a stunning display of color that is sure to impress.