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
Old School Garden 
Strange that the Cannon ball flower is a native of South America because I think the guide said it was the national flower of Cambodia! Thanks for a all the botanical enlightenment over the past few weeks, love to you and Deb and have a good Christmas in Portugal. Xx
Thanks Jen, I think the national flower of Cambodia is called Rumduol (Mitrella mesnyi), whose large rounded buds are similar to this plant. I’ve also corrected the post, as it appears the name ‘Cannonball Tree’ refers to it’s fruits (which can grow to 25cms in diameter!), rather than the flower buds; it’s also sacred to Hindus!
One further bit of information! You’ll see the name of the tree on the trunk as Pentacme siamensis..it appears that this is a locally given name to Couroupita, but is incorrect. I also gather the tree is sacred to Buddhists and Followers of Jainism as well as Hindus!