Papaya

Carica papaya is not quite a tree in the conventional sense. It is a giant soft-stemmed herb that behaves like one, throwing a single unbranched trunk topped by a crown of deeply lobed leaves up to a metre across, and carrying fruit almost continuously from its second year.
In landscape work it is used for immediate tropical effect. It reaches useful height inside two seasons, occupies almost no ground, and is replaced every four or five years as the crown lifts out of reach.
Papaya delivers tropical scale faster than any woody tree, on the understanding that it is a short-lived component of the scheme.