So, here are the final four wonderful pictures taken by my friend Jen over in Vietnam.
First, a plant with a common name of ‘Canonball Tree’ due to its large rounded fruits (and its flower buds also rather resemble Brussel Sprouts!). Couroupita guianensis, as its name suggests, was originally native to South America.

Couroupita guianensis
Second, one of the range of River Lilies Crinum. I think this one might be the ‘giant Spider Lily’ Crinum x amabile, which can grow to 6 feet tall in the right conditions.

Crinum x amabile
‘Folded and floating’ is how Jen describes these amazing Lotus flowers…
Finally, this one caused me a lot of searching (including via our postman’s Vietnamese friend!), but I’m pretty sure its the ‘Cockspur Coral Tree’ or Erythrina crista-galli (the latter means ‘cock’s comb’). A native of South America it is also the national tree and flower of Argentina. The picture shows the dramatic terminal raceme of flowers, in this case not yet open.

Erythrina crista-galli