The Empress tree (Paulownia tomentosa) is a fast growing deciduous tree species native to China but widely used in parks and gardens in many countries. Its soft blue bell shaped flowers form in a cluster (panicle) prior to the new leaves in Spring. the leaves are heart shaped and quite large measuring sometimes up to 30-40 cm across.
The seed pods of this tree species are about the size of a golf ball and pointy on one end. When mature they crack open and release numerous small seeds that are disbursed by the wind.
The shape of the opened seed pods reminds me quite a bit of a nest of young birds with their beaks wide open as they await their next meal soon to be delivered by their mother.
Some years back when I lived in Portland Oregon I was charged with the task of removing what was thought to be a fast growing weed that was growing too close to the side of a building. We later discovered that it was in fact an Empress tree that did not at all want to be removed! Within a few weeks of having chopped it off at the base it had regained its original height. I removed it again and this time dug up the main bulk of the stump. A few months later it was growing back again having recovered from some of the roots that I had left. We gave up the fight for that year and let it grow. By the next year it was more than 15 feet tall growing right up against a large window. We were finally able to remove it completely and keep it from growing back, but not before gaining a very healthy respect for this tree species tenacity and obstinate persistence. No wonder it has become invasive in some parts of the US.
For a tree with similar flowers check out the Blue Jacaranda.
For a tree with similar leaves try the Indian Bean Tree (Catalpa).
For a tree with big extravagant leaves and interesting flowers try the Snowflake Aralia.