PlantFiles: Iron Wood, Leopard Tree, Brazilian Ironwood
Caesalpinia ferrea

As long as seeds are scarifyied they will germinate well in soil with a good supply of nutrients and well drained. I have a Brazilian Ironwood tree at my front garden and it developed so fast in two years that it is already bearing the first flowers, although it will take a few more years to grow its trunk in diameter and develop a more wide crown.
See the pictures I have added

Called Leopard Tree or Leopard bark because of its beautiful mottled bark and Brazilian Ironwood for its hard wood which is dark brown with thin black streaks. Unlike many of the Caesalpinia this species is not thorny. Native to South American.

This is a big tree, reaching up to 30m tall, from the brazilian tropics. Its common name comes from its very hard wood, that is the main atractiveness of this plant. It has a thin grey bark that falls constantly, revealing an uncommon white wood that looks like made of ivory.

The small leaves and tiny leaflets are constantly renewed, so you may have some work to keep the ground clean. The yellow flowers are unoticeable in largest individuals. The fruits are dark brown, hard, and won´t rippen easily, but it´s kinda sweet inside, and birds like it.